Quietmeyer on Early Cement: 1911

Joseph Aspdin (1779-1855)

The product marketed under the name "Portland Cement" since 1825, originated in a small factory in Wakefield, which the owner, a bricklayer, Joseph Aspdin from Leeds, built after he had acquired patent No. 5022 for "An improvement in the modes of producing an artificial stone" on October 21, 1824.

It is widely believed that Joseph Aspdin is credited with the invention of Portland cement not only by name, but also by the method of production. The reason for this can be found in the note in the patent description:

. . . and which I call Portland cement.

But Aspdin's invention was far removed from what is understood by this term today, perhaps even further than Frost's. First read the wording of the description with which Aspdin justified his patent claims. (see Patent).

On June 7, 1825, Aspdin took out another patent under No. 5180 for the burning of road dust without the addition of clay. The resulting product was to be used as lime for construction and for agricultural purposes. This "invention" is therefore of no relevance to the present work.

The first patent indicates that it is an artificial product made of lime and clay, which differs from St. Leger's mixture only in that the composition, when using road mud, had to be very variable.

Regarding the degree of firing, the inventor says that he only increases the heat until all the carbon dioxide is expelled from the mixture; Nevertheless, he does not produce a slaked lime, but rather a Roman cement, as is evident from the statement that the fired mass is subsequently to be ground into powder.

According to his son William, Aspdin began his experiments as early as 1811. Therefore, he cannot have been aware of the results of Vicat's work; Dobbs's invention of 1810, which is somewhat reminiscent of his own, was undoubtedly unknown to him, for even though hardly any patents are published today as clearly and as easily accessible as the English ones, it was still extremely difficult to obtain further information about them, except from the patent office itself (Note 1).

It is therefore likely that the success of Parker's cement, or perhaps Smeaton's publication, further spread the word about the hydraulic properties of a material fired from lime and clay, and thus prompted attempts to produce such cements artificially.

The inventor named his product "Portland cement" because of its similarity in colour to Portland stone, which was very popular in England as a building stone.

To exploit the patent he had obtained, Joseph Aspdin founded a small factory in 1825 in Wakefield, near his former home in Leeds. To extract the lime for the raw mixture, apart from the mud from limestone-paved roads, only hard stone was available to him, so that, due to the lack of suitable grinding equipment, he was forced to first burn the stone and then slake it into powder (Note 2). His first factory later fell victim to the construction of the railway, so he was forced to build a new one, which he managed until the end of his life. The factory was then continued by his second son, James (Note 3), under the name "Aspdin & Son", and was only recently closed down (Note 4).

The factory does not appear to have achieved any great importance; its location was favourable neither for the procurement of raw materials nor for the sale of the product. It is therefore reasonable to assume that no significant improvement of the product took place in Wakefield (Note 5). It was only the inventor's eldest son (Note 6), William Aspdin, who captured a wider field for the dissemination of the new mortar.

When attempting to determine what we mean by the term "Portland cement" of the time, it is extremely difficult because the records from that time are very scanty. Even in the homeland of the invention, very little authentic information can be found (Note 7). It would seem likely that the name "Portland cement" refers to the colour and, from this, the degree of firing of the new mortar. But unfortunately, this definition fails.

The Portland stone, which inspired the name, is mined near Portland from two layers, one of which is called the "base bed" and the other the "white bed." The very fine-grained oolitic limestone is reminiscent in colour and grain of our modern-day sand-lime bricks. Those made with very pure quartz sand resemble the lighter variety, while those made with a slightly iron-rich sand resemble the somewhat more yellowish one. Neither deposit bears the slightest resemblance in colour to our modern-day Portland cement, but the yellowish variety is reminiscent of that of a lightly fired clinker, so that the choice of name would initially only suggest a weak firing (Note 8). However, in industrial areas, these bricks are said to soon take on a blue-grey-green hue under the influence of smoke-filled, humid air, similar to that of the hard-burned Portland cement of later times (Note 9). The term would therefore indicate a soft burning in smoke-free areas and a hard burning in reduction areas, and is therefore irrelevant for the assessment.

Undoubtedly, the original assumption, that Joseph Aspdin only burned softly, is the correct one. First, the inventor himself stated that he only burned until the carbon dioxide was expelled, for which he theoretically required a temperature of just over 800°C, but in practice probably used a temperature of around 1000°C. Furthermore, one must realize that the grinding equipment of the time was not suitable for grinding hard-burned clinker. Its poor efficiency even forced the company to avoid grinding the raw limestone and to burn it before mixing. And after all, someone who only knew Roman cement could hardly have wanted to invent anything other than an artificial substitute!

There is also direct evidence, however, that Aspdin not only burned softly, but even discarded any clinker that had accidentally been burned to the point of sintering (Note 10). Even his contemporary, Colonel Pasley, the "Vicat of the English," who had been involved in the manufacture of cement since 1826, never wanted to produce anything other than soft-burned cement (Note 11) and dumped all sintered clinker. The advantages of firing to the point of sintering was only recognized through experience, and this took many years.

We must therefore imagine the Portland cement of the 20s and 30s as a soft-burned cement, which today would simply be called Roman cement.

Initially, this product was used almost exclusively for plastering buildings. It was Brunel who first initiated its use for civil engineering projects when, starting in 1828, he preferred it to the Parker's cement previously exclusively used (Note 12), during the construction of the Thames Tunnel, although the price was almost twice as high as that of the latter. Given Brunel's conscientiousness, one must assume that he first subjected the new mortar to thorough testing before deciding to use it and thereby established its superiority (Note 13).

Although it was a weakly fired product, a generally satisfactory raw mixture appears to have been achieved. The road mud, which Joseph Aspdin originally intended to use according to his patent description, probably only provided sufficient raw material for the initial stages of production; when demand was somewhat greater, limestone was undoubtedly required, and this eliminated the worst fluctuations in the mixture. Thus, weakly fired, but nevertheless an often favourable composition, is what one must imagine the product of that time to be. And later history teaches us that a quite usable cement could still be achieved with it. Portland cement had long been used for the most important work, long before all soft burning had been eliminated, indeed, before sintering was even largely adopted.

However, it must be kept in mind that Aspdin, with his complete lack of chemical knowledge, did not always succeed in achieving a uniform mixture; even 20 years later, we still frequently hear of deformation, the collapse of cornices, in short, of imperfections in the product, which, although only occasionally occurring, were not entirely impossible even until recently (Note 14).

The Aspdin process does not appear to have achieved any significant widespread use for almost two decades. The small factory in Wakefield, whose capacity was very limited, remained for a long time, even after the patent expired (1828), the only one producing the new mortar. This explains why Pasley first heard of Aspdin when he encountered its products at the London Exhibition in 1851 (Note 15).

Nor does it seem to have been known in other English professional circles. In the widely-used technical dictionary Dr Ure's Dictionary of Arts, Manufactures and Mines, both the first edition of 1839 and the third edition of 1846, only mention natural Roman cement. In contrast, the fifth edition of 1860 (the fourth edition was not available to me) contains a detailed discussion of Portland cement.

William Aspdin (1816-1864)

As already mentioned, it was William Aspdin who was the first to introduce significant improvements in the manufacturing process of the artificial Roman cement marketed by his father under the name Portland cement.

William Aspdin, who presumably spent his apprenticeship in his father's factory, first entered the public eye in 1843 as managing director of the Maude, Son & Co. factory, which was founded at his instigation. The company consisted of a small facility with only one kiln (Note 16) in Rotherhithe, London.

Although it existed for only a short time, this factory was indirectly of great importance for the maturation of the initial product into the true "Portland cement".

It is difficult to determine whether this factory had already partially fired to the point of sintering. An advertisement for the company in question from 1843 particularly emphasizes that its product had the colour of Portland stone, but according to the above, this could only be achieved on condition that it was lightly fired. Redgrave and Spackman (Note 17) assume that the clinker consisted of a mixture of lightly fired and sintered material. I C Johnson, over 100 years old and the only witness of that time still alive at the time of writing, was of this opinion. According to the information he sent me in letters, there was undoubtedly a small amount of sintered clinker alongside predominantly lightly fired clinker. The isolated data on the density of the cements of that time lead to similar conclusions. For example, Frost's cement from White & Co. had an apparent density of around 0.90 (Note 18). However, in 1843, Maude, Son & Co. reported the figure 1.13 for their so-called Portland cement (Note 19). This also indicates a fairly light firing. Aspdin never seems to have succeeded in producing a consistently sintered clinker. When he managed a small factory in Holstein a few years before his death, according to letters from Michaelis, light firing was still commonplace there.

Above all, however, the uniformity of the product was poor; even a full 10 years after the period I am speaking of here, the cement was generally quick-setting and not infrequently unsound (Note 20).

This is hardly surprising. Aspdin's chemical knowledge was decidedly very limited. This is confirmed by correspondence from Dr Heinzel from Lüneburg, where Aspdin had found employment from 1860 to 1862 in the construction and operation of the Portland cement factory. Even then, he was not yet able to perform an analysis of the raw materials (Note 21). If the cement was unsound, he added less lime; if it crumbled, he used less clay.

The necessary conscientiousness also seems to have been lacking. Johnson accuses him (Note 22) of adding ground blast furnace slag to the cement and, in Gateshead on the Tyne, where he lacked chalk, of using lime residue from a soap factory.

Perhaps somewhat caught up in alchemical beliefs or striving to mystify his workers, he occasionally threw handfuls of copper sulfate, iron sulfate, bone meal, and other substances from a secret box onto the fuel in the kiln (Note 23).

If one draws the conclusion from what has been said, one can imagine Aspdin's cement around 1843 as a product which generally had a high clay content, was predominantly lightly fired, and whose composition frequently changed.

Nevertheless, Maude, Son & Co. managed to draw attention to their product. Experiments conducted in 1843 by the large London contractors Grissel and Peto comparing Portland cement with Roman cement (Note 24) demonstrated the significant superiority of the former. Although the price was almost twice that of Roman cement, the mortar made from it was cheaper, because a larger amount of sand could be carried; a 1:3 mixture still produced significantly higher strengths than a Roman cement mortar with only one part sand.

Nevertheless, the financial results of the very small Rotherhithe business were not favourable (Note 25), and the factory, which in 1846 bore the name "Maude, Jones & Aspdin", does not appear to have lasted long. We find Aspdin in Northfleet as early as February 1848, in association with a lawyer named Robins (Note 26).

In 1848, the new factory, which initially operated with several kilns (Note 27), conducted further experiments to prove the superiority of Portland cement over Roman cement. Invitations were sent to other factories to participate in public strength tests. At the London Exhibition of 1851, which was also attended by White, who had also started production of Portland cement, the Robins product received a favourable assessment in that it was considered "at least equivalent" to White's (Note 28). Without doubt, Aspdin, who must be considered the actual plant manager, had perfected his process over the years to such an extent that by 1851, at least in smaller quantities, he was able to produce a cement that could compare with that of the carefully operated White's factory. That progress had been made in firing is also evident from Becker's data (Note 29) from 1851 and 1852, according to which the bulk density of both Robins' and White's cement was 1.21 at that time. However, whether such a good product was regularly produced at the Robins factory must be doubted, given Johnson's reports on the inadequate preparation of the raw materials, with which Aspdin was satisfied (Note 30), as well as the reports of his later, unsatisfactory performance. Presumably, the irregularities caused by the consumption of strong drink were already reflected in the performance of his factory management (Note 31). In short, his stay in Northfleet was not long. He resigned in 1851 (Note 32). He then changed his location more and more frequently, finally moving to Germany, where he met an early end in 1864.

He was evidently a gifted man, but one who lacked any scientific training. He developed the limited knowledge of cement technology that he had been able to acquire up to the age of 25 at the small works in Wakefield, and he may have succeeded in bringing his father's invention closer to what is known today as Portland cement by gradually changing the mixture of raw materials and gradually introducing more intense firing. That he deliberately fired to the point of sintering or aimed for such a process is nowhere stated, and many statements speak against such an opinion.

Isaac Charles Johnson (1811-1911)

As mentioned, in 1843, the experiments of the contractors Grissel and Peto, during the construction of the new Houses of Parliament, drew attention to the new mortar, which was superior to Roman cement.

Although the company of Maude, Son & Co., which brought this product to market, was small and hardly formidable in terms of competition, the enterprising firm of John Bazley White & Sons immediately decided to begin producing a similar cement.

The manager at that time was Isaac Charles Johnson (Note 33), who was wealthy and working as a cement manufacturer at the time of writing this, was born in London in 1811, the son of an employee of the Francis & White factory.

White's initial intention was to make a deal with William Aspdin, but the idea was abandoned after Johnson declared that he was committed to producing a product equal to Maude's.

At that time, the Whites factory burned Roman cement from the septaria of Sheppey and Harwich, as well as hydraulic lime, especially for export to the West Indies, and the artificial Frost cement, which, as already mentioned, was composed of 2 parts chalk and 1 part Medway clay and therefore did not differ significantly from Pasley's in its raw mixture.

To fulfil his promise, Johnson initially saw only one option. Gaining a glimpse into Aspdin's factory was impossible: a 6-metre high wall surrounded the plant, and the only access led through the office. The workers knew nothing about the raw material mixtures, as Aspdin was adept at misleading them with his aforementioned secrecy, which he succeeded in doing all the more easily since he himself had no clear understanding of the chemical processes involved.

So Johnson resorted to analysis. To be absolutely sure, he handed the samples taken from the store to one of the most eminent chemists of the time, Dr Ure, editor of a chemical journal (Note 34) and member of the Royal Institute of Chemical Analysis in London. Strange results emerged that are almost impossible to explain: the "blue-gray mass", whose origin had not been disclosed to Dr Ure, was said to contain no silicic acid at all, but rather 10% calcium carbonate and, above all, 45% calcium phosphate. The report read:

Analysis of a blue-grey mass for Mr I C Johnson, 16 April 1844 by Andrew Ure MD, FRS etc.

Perhaps the samples were mixed up, or there was some other error (Note 35). Be that as it may, Johnson believed the information, which is hardly surprising given the state of cement research in England at the time and the search for a mystical "something" that would give lime its underwater hardening properties.

When all experiments with mixtures of phosphate of lime in the form of burnt bones proved unsuccessful, Johnson decided to trust his own chemical knowledge and first analyse the proven septaria from Harwich and Sheppey. He discovered what he would have discovered more quickly from the studies of Smeaton and Vicat: that a mixture of lime and clay, i.e. what he had long used in Frost's cement, forms the basis of all cement. Thus he was able to begin to achieve his goal with the help of experiments, using a wide variety of mixtures and firing temperatures. While it is surprising that the man did not turn to books that could have provided him with instruction, one must nevertheless acknowledge all the more that in the course of a few months he succeeded in arriving at a satisfactory mixture and, above all, in realizing that firing to the point of sintering was the main requirement. However, many errors occurred before the goal was achieved. Johnson once went as far as a mixture of 5 parts chalk to 1 part clay. He obtained strong cement, which he set aside. After weeks of other work, he saw that the clinker showed clear traces of slaked lime. He now knew the composition was too calcareous, so he went back to 5 parts chalk to 2 parts Medway clay and stuck with this mixture, firing it with unusually strong heat until the mass was nearly vitrified (Note 36).

It has already been mentioned that the clay extracted from the Medway has a greatly varying lime content (Note 37). For example, in his 1836 experiment, Pasley (Note 38) had to reduce the clay content of the raw mix by 11% compared to the 1828/29 mix in order to obtain a cement of the same quality. This must be taken into account when assessing the mixing ratio. However, if we ignore Pasley's data, which are not supported by any analysis, and use only that of Gillingham (Note 39), according to which the Medway clay contains, in addition to a few percent lime and magnesia, about 87% silica + aluminium oxide + iron oxide, we can see that the mixture of 5 lime to 2 clay was not as clay-rich as it appears at first glance, and that this results in a so-called hydraulic modulus of about 1.6. This also agrees with the analyses of English Portland cement that Hopfgartner published in 1849 (Note 40). Although it is not stated whether the samples came from the White or Robins factory, the results provide some idea of ​​the composition at that time. Therefore, the investigations carried out according to Pettenkofer's method are presented here.

The cement contained:

This corresponds to a hydraulic modulus of 1.56.

Thus, thanks to firing to the point of sintering, Johnson had achieved a quite usable, genuine "Portland cement". But not satisfied with this success, he now turned his attention to careful rawmix preparation (Note 41), emphasizing that only such processing could produce a uniform product and that the irregularities of Aspdin's cement were due to the lack of a sufficient mixture of raw materials.

Now, at last, the main requirements for the manufacture of a product corresponding to today's concepts of Portland cement have been met; the establishment of a raw mixture requiring only minor improvement is the principle: "firing to the point of sintering". And so the year 1844, in which Johnson completed his experiments and the modern factory began selling the new product, is to be regarded as the true birth year of Portland cement (Note 42). But the man who, in all probability, was the first to recognize the sintering required to produce a high-quality cement and who strove to implement it to the best of his ability, is indisputably a completely independent inventor of the manufacturing principles still valid today for the manufacture of Portland cement. According to what has been said above regarding William Aspdin (Note 43), the same can hardly be claimed for him.

Johnson continued to work diligently on improvements, not only in the rawmix preparation but also in the combustion process. The kiln he invented, which utilizes the heat from the exhaust gases to pre-dry the raw material prepared as thick slurry, enjoyed great importance in England for a long time.

This tireless man became a true pioneer in the field of cement manufacturing. It is also to be acknowledged with gratitude that, even at the ripe old age of almost 100, he took up his pen and wrote down many details about the history of his works that would otherwise have been lost forever. This is not the place to follow the life of this rare man any further than the story of the invention of Portland cement requires. Anyone wishing to learn more about this self-made man will find more details in the sketch (Note 44) already mentioned, as well as in the appendices to this work.

The most important link in the series of cements had now seen the light of day. Many participants oversaw its development, first and foremost the practical English, who strove to promote its growth as far as they could. Then, as intellectual champions, above all the Germans and the French. A considerable number of researchers from these two countries devoted themselves to the scientific investigation of its properties. They were joined by those from other countries, particularly Russia and, most recently, America. And thanks to these universal efforts, the new cement material achieved a level of perfection in a relatively short time, which ensures its daily wider distribution, makes it appear suitable for ever new purposes, and — especially in combination with iron reinforcement — offers construction technology the means for the boldest designs.

There is little to add to what has been said above about Joseph Aspdin, the inventor of the Roman cement (Note 45) he marketed under the name "Portland Cement". He was born in Leeds in 1779 (Note 46). His occupation was a bricklayer (according to the patent specification, "bricklayer", according to Johnson, "builder"). He personally managed the factory he founded in Wakefield until 1853 (Note 47). He died on 20/3/1855. How much he himself contributed to the gradual development of his initial product into true Portland cement is not certain; the experiences his son William gained over the years were probably also used at the Wakefield factory.

William Aspdin, Joseph's elder son (Note 6), was born in 1816 (Note 48), presumably in Leeds. Nothing is known about his early life. He doesn't seem to have paid much attention to his education (Note 49). According to inquiries I was able to gather about him in Lüneburg, his knowledge was still rather lacking even toward the end of his life (Note 50). We traced his first independent activity from 1843 above and saw that in 1848 he moved from Rotherhithe (London) to nearby Northfleet (Note 51), where he remained until 1853 (Note 52). He then turned north and leased an old flour mill in Gateshead, opposite Newcastle upon Tyne, which he converted into a cement factory. Due to persistent non-payment of the rent, the owner soon terminated the lease. Nevertheless, this enterprising, if restless, man seems to have once again succeeded in attracting financial backers. The fact that his father was considered the inventor of Portland cement and that he himself had sole knowledge to the manufacturing secret was too favourable a recommendation. A small pamphlet from 1854, published by Aspdin, Ord & Co., names London and Gateshead as the headquarters of their company and states the weekly output of both plants as 3,000 barrels (Note 53). It has not been determined when this connection was severed. Then Aspdin appears to have once again attempted to establish a company that was significant for its time. In The Builder of March 1880, there is only a brief comment on this, omitting any date, according to which Aspdin began a large establishment, "Portland Hall" near Gravesend on the Thames, the construction of which would have required an expenditure of over £40,000. But before a third of the work was completed, such financial difficulties arose that the builder was forced to sell the unfinished work at a great loss (Note 54).

This collapse forced Aspdin to leave England. He went to Hamburg, where we find him in 1855 (1856?). In 1857, he succeeded in persuading a coal wholesaler named Fawcus, who came from Newcastle (Note 55), to build a cement factory. The factory began operations on October 23 of that year; it was sold and closed in the early 1860s.

Aspdin had already made the acquaintance of a Lüneburg lime kiln owner who was not averse to entrusting him with the construction of a factory. However, the venture fell through because the information gathered about Aspdin was unfavourable. However, after leaving the Fawcus factory, the latter managed to secure other backers for his proposals. Thus, from 1860 to 1862, we find him involved in the construction and operation of the Lüneburg Portland cement works. He was dismissed from there because his performance fell short of expectations. He then returned to Hamburg, where he once again found money for a new venture. An Englishman named Fewer agreed to build a small factory in Lägerdorf near Itzehoe, the site of extensive chalk deposits. This factory still exists today as part of the large Alsen company. But barely had operations begun when disagreements led to another split between the parties. Aspdin received a severance payment of £250 and moved to Itzehoe. He seems to have increasingly taken to alcohol, which had previously been the cause of recurring quarrels with his partners and was also the direct cause of his death. A multiple rib-fracture, the result of a fall, brought about the end of the man in 1864 at the age of only 48 (Note 56).

Johnson was born on 28/1/1811, in London (Vauxhall). His parents were working-class people. His schooling was limited to reading, writing, and arithmetic. As a 14-year-old boy, he took a job with a bookseller in Craven Street, Strand, where he was required to man a stall and cart books. Although this offered ample food for his penchant for reading good authors, the job was too strenuous in the long run for the frail boy, who was the constant concern of his mother. So, in 1827, at the age of 16, he was sent to work at the Francis & White factory in Nine Elms, in the London suburbs (Note 57), where his father worked. Initially, he was assigned to an Italian gypsum burner, then moved through the other departments of mortar manufacture, and finally landed a supervisory position in the construction of kilns and chimneys. But convinced that advancement would be difficult, he urged his father to let him learn a trade, and so he began an apprenticeship in a carpenter's workshop in 1828. In the evenings, he attended a continuing education school, studied chemistry and mechanics, and created small designs. Soon, he was able to swap his workbench for a drawing board and, during his free time, teach young craftsmen.

Meanwhile, White had acquired the Frost cement works in Swanscombe and, in 1835, invited Johnson to rejoin him. Just one year after his appointment, he was entrusted with the management of the cement factory, where the chemical knowledge he had acquired proved very useful. His bosses left him virtually sole control of the operation and accordingly granted him an annual salary of several hundred pounds. Production continued without any notable incidents until 1843. Then, however, the product of the Maude, Son & Co. factory in Rotherhithe (London), founded by William Aspdin, caught White's attention and fuelled the desire to offer a product equivalent to Aspdin's "Portland cement", which was apparently superior to the Frost cement previously produced in Swanscombe.

Now came the period of experiments for Johnson, described above, which led, at the end of 1844, to the factory-scale production of a Portland cement similar to today's (Note 58). Johnson improved the slurrying process used for processing by using fairly large agitated tanks with a diameter of 4.5 m, then allowing the slurry to pass through grinding mills, conveying it to an elevated mixing trough using a bucket elevator, and there subjecting it to further processing by a knife shaft. He thus achieved an excellent processing result, somewhat reminiscent of today's thick slurry process. Although he had been entitled to a certain share of the factory's net profits since 1847, he resigned from management in 1849 to establish his own small factory in Rochester on the Medway. There he found a former oil mill equipped with steam power, which he leased for 2½ years. He built the necessary kilns and drying chambers at his own expense. Since the contract was not renewed, Johnson leased chalk land from Lord Darnley in Cliffe on the Thames, near Gravesend, in 1852 and established a small new factory there, which eventually grew to a considerable size. Shortly thereafter (Note 59), Johnson, unintentionally, came to a second factory, far north of Cliffe, in Gateshead, opposite Newcastle upon Tyne, where some coal mine owners proposed that he continue to operate the factory formerly run by William Aspdin.

It was here, around 1854, that he invented the kiln named after him, which still plays a role in England today, where not replaced by the rotary kiln. This is a static kiln with intermittent operation, whose exhaust gases flow through a long, horizontal flue to a central chimney. Along the way, they dry the raw material pumped into the flue as slurry, allowing it to be removed after firing and thrown into the kiln for the next burn.

Sales increased and the Cliffe factory could no longer meet demand (Note 60), so in 1873 a third factory was built in Greenhithe, also on the Thames, not far from Cliffe.

The former factory worker managed these three plants as president and advisory director until the end of his life. He also found time to take on various honorary positions in the poor relief charities and the Temperance Movement. Photography was his recreation. At the age of 87, he decided to take up cycling and pursued this sport with great enthusiasm. He only retired from his steel horse at the age of 98. After learning ancient Greek, the old man began translating the New Testament from that language into English in his spare time. On January 28 of this year (1911), he turned 100 in virtually undiminished health. To celebrate this rare event, the English Portland Cement Manufacturers' Association presented the Nestor of their industry with a valuable gift of honour. The associations of North America, Germany, and Russia sent their congratulations in the form of addresses, and he received hundreds of congratulatory telegrams from all over the world. Johnson's astonishing physical fitness, his almost undiminished work ethic, and his willpower gave rise to the hope that he and his friends would be able to celebrate January 28th more often. This hope was not to be fulfilled. On November 30, 1911, his life, equally rich in work and success, came to an end in the modest villa "Mayfield House" in Gravesend.

With Johnson passed the last of the men whose activity reached back to the early years of the cement industry, a pioneer of this industry, who succeeded earlier and more perfectly than his competitors in trying to transform the artificial Roman cements introduced by Frost and Joseph Aspdin into Portland cement.