TRANSACTIONS OF THE SECTIONS. 183 
to superheat the steam; to jacket the cylinders to warm the injection water; to 
work the steam expansively by having two cylinders, a small one at the back of the 
large one, or concentrically within the large one, and to let the steam into the small 
eylinder first. Although he recommended this to our Admiralty in 1855, no notice 
was taken of it. The Swedish Government have adopted it in their new gun-boats, 
and it obtained a medal at the present Exhibition. By these arrangements for 
economy, and with better-designed engines, 17,000 tons of coal per day might be 
saved throughout our fleet; but now, after steaming 2000 miles, the ships have to 
ereep into port, under canvas, to be re-coaled. 40 per cent. of power might be 
added, and therefore a greater speed of one-and-a-half knot per hour obtained, 
without greater displacement; and 14 tons per horse-power per annum, or a mil- 
lion tons of coals per annum, for the whole fleet might be saved. 
On Artificial Stones. By Professor D. T. Ansrep, M.A, 
In this paper the author described the various materials and contrivances used 
for the purpose of replacing stone where natural stone could not be advantageously 
procured. He described, in succession, terra cottas, cements, and siliceous stones, 
ointing out the character, properties, uses, advantages, and disadvantages of each, 
e alluded to experiments made in the laboratory on the various methods sug- 
gested for preserving stone by a Section of the Committee recently appointed by 
the Board of Works in reference to the Palace of Westminster; Dr. Hofmann, Dr. 
Frankland, Mr. Abel, and the author being members of it. During their investiga- 
tions a remarkable material was submitted by Mr. Ransome for their considera- 
tion, and its discovery arose out of Ransome’s method of preserving stone by 
effecting a deposit of silicate of lime within the substances of the absorbent stone, 
saturating the surface with a solution of silicate of soda, and then applying a solu- 
tion of chloride of calcium ; thus producing a rapid double decomposition, leaving 
an insoluble silicate of lime within the stone, and a soluble chloride of sodium, 
which could afterwards be removed by washing. To prove this, Mr. Ransome 
made small blocks of sand in moulds by means of silicate of soda, and then dipped 
them in chloride of calcium. The result was the formation, almost instantane- 
ously, of a perfectly compact, hard, and, to all appearance, a perfectly durable 
solid. Mr. Ransome at once adopted the process for the formation of an artificial 
stone which, the author of the paper considered, would combine the advantages, 
and avoid some of the disadvantages, of other artificial stones. Experience, how- 
ever, can alone be the test of its durability. A specimen weighing two tons was 
shown in the International Exhibition, and the substance is used in the stations of 
the Metropolitan Railway. Itis cheap, and can be made, on the spot, of almost any 
rubbish or material, and of any form or size. Experiments made by Mr. Ransome 
show that, as compared with Portland stone or Caen stone, a bar with section 4 
inches square and 8 inches long, suspended midway between supports, sustained 
2122 lbs., while similar bars of Portland and Caen stone broke respectively with 
750 lbs. and 780 lbs. The adhesion of the stone was shown by weights suspended 
from a piece prepared to expose a sectional area of 53 inches. Caen stone sepa= 
rated at 768 lbs. ; Bath, at 796 lbs.; Portland, at 1104 Ibs.; Elland Edge, at 1874 Ibs.; 
Ransome’s, at 1980Ibs. A cube of 4 inches of Ransome’s stone sustained 80 tons. 
Unsinkable Ships. 
By Cuares Aruerton, late Chief Engineer in HM, Dockyard, Woolwich. 
The author observes that competitive rivalry in the construction of ships of war 
with a view to their being “invulnerable,” and in the construction of ordnance 
with a view to its being effective for penetrating the build even of armoured ships, 
appears, from the experiments which have been carried on at Shoeburyness, to be a 
question involving unlimited penne in possibly abortive ship-building, the 
‘yesult of which rivalry between ordnance and iron plating, being dependent on future 
invention, does not admit of present definite solution. 
Nevertheless the principle of “invulnerability” in the construction of ships of 
war by the agency of iron plating having been originated and adopted by France 
; present the most effective system of naval construction, though admitted 
