TEANSACTIONS OF THE SECTIONS. 249 



there ceased to be any imcombined lime to decompose the silicate of soda produced, 

 the termination of the action being marked by the presence in the pores of the 

 stone of the excess of caustic soda in the one case, or of silicate of soda in the 

 otliei'. In reality, however, the whole of the caustic soda does not appear to be 

 set free each time the silicate of soda is decomposed by the lime, there appearing 

 to he formed a compound silicate of lime and soda, whereby a small portion of the 

 latter is fixed at each decomposition. The result is that the caustic soda is gradually 

 fixed, and none remains to be removed by washing or the other process. 



At the age of 10 weeks, in stones made by this process, the strength as compared 

 with Portland stone was found to be as 714y lbs. to 2630 lbs. per square inch, and 

 as compared with Bramley Fall 714;0 lbs. to 5120 lbs., and as regards granite 

 714o lbs. to 1200 lbs. per square inch. With reference to durability, it has been 

 fouud practically to withstand the atmospheric changes of various climates, havino- 

 been exposed to the cold of Russia and the heat and rains of India. In general 

 appearance it beai-s such a perfect resemblance to the best description of natural 

 stones as to mislead the most critical observers, whilst the facility of application 

 and its economy in use will have been apparent from the foregoing description. 



By means of this process the field has been widely extended for the application 

 of the stone produced thereby, and which for convenience, as distinguishing it from 

 all others, has been termed Apcenite. It is now no difficult task to produce blocks 

 of this material of any form and of any size, the only limit being the means 

 available for handling them upou the spot where they are to be employed. More- 

 over, the materials which form the bulk of apo3nite are, as a rule, generally to be 

 fouud in abundance where hydraulic or other important works are being carried on, 

 and for which purposes the new stone is eminently suited. 



The want of such a material for such a purpose has long been felt, although that 

 want, until recently, has only been partially supplied. In 1870 Mr. J. W. Butler 

 applied for and obtained a patent for improvements in the application of Concrete 

 to Structures and Foundation, also to Ooft'erdams and similar constructions. Mr. 

 Butler's obvious desire was, in the first place, to provide a cheap and efficient sub- 

 stitute for stone for hydraulic operations, and in the second to render unnecessary 

 the construction of false works, Sec, and thus to avoid the expense connected with 

 the employment of iron cylinders, hitherto so extensively used. The idea was 

 certainly an excellent one, but in realization appeared to Mr. Butler very remote, 

 until it occurred to him that the material then introduced under the name of 

 " apcenite " would answer the purposes of his proposed methods of construction. 

 lie accordingly communicated with the author upon the subject ; and with the 

 sanction of the engineer, a set of hollow cj'liuders 8 ft. in diameter and 9 in. thick 

 were made to form a part of a retaining wall to protect the foreshore of the Thames 

 at Hermitage Wharf, where they were accordingly sunk, and tlie result was satis- 

 factory. 



The application of this principle is capable of modification to suit almost every 

 variety of construction, and it will be found especially applicable in structures 

 requiring heavy foundations, particularly where the ground is uncertain. 



For forming a face-wall in building quays or docks, instead of cylinders, 

 rectangular hollow blocks or caissons may be used. By emploj'ing hollow blocks 

 of hexagonal form no interstices are left, a thin layer of the cementing material 

 rendering the structure practically homogeneous. Cj'linders constructed upon tliis 

 principle are also adapted for deep wells, apertures being formed in the sides for 

 the admission of wfiter. 



Turning to works of greater magnitude, it will be seen that apcenite forms a 

 suitable substance for the construction of bridges, sea-walls, piers, and similar 

 undertakings. Such structures could be carried iip to the underside of the bridge- 

 girders, or built with ordinary masonry above high-water level. For sea-walls or 

 piers another arrangement could he adopted, two rows of caissons being emplo^'ed, 

 separated from each other longitudinally, the intermediate space being filled in with 

 dry rubble hearting, and the bloclcs themselves with a similar material or, if 

 necessary, with concrete. 



It would not be difficult to multiply the instances in which this material can be 

 practically applied ; but suffi.cient has been said on this point. An artificial stone 



