35 
be effected by covering them with paint or other oleaginous matters 
holding various substances in solution; but from their very nature these 
must all be ineffective, on account of the speedy decomposition they 
undergo. Bituminous or pitchy matters are the only solutions of this 
class which are at all likely to be permanent, but the unsightly appear¬ 
ance they give to the structures on which they are used is an insupe¬ 
rable objection to their use. Attention must then be directed to the 
mineral kingdom, and here we must find a substance or substances 
capable of firm adhesion, and not liable to be acted upon by 
those agencies which exist in the atmosphere, and are capable of 
effecting the destruction of stone. More than thirty years ago. Dr. 
Fuchs, of Munich, discovered a soluble compound of silica with an 
alkali, and called it water-glass. This solution, exposed to the air, 
becomes viscid, opaque, and then hard, in consequence of the carbonic 
acid of the air abstracting the alkali and liberating the silica. Dilute 
acids produce a similar result. Mr. Kuhlmann, of Lille, in 1841, 
began the publication of a series of papers on this subject, which were 
continued up to 1857. Observing the hardness produced in chalk by 
immersion in a solution of water-glass, he thought this might be used 
for the hardening of stone. He proposed to cover buildings with such 
a solution, after cleaning the surface. In 1844 Mr. Ransome, of 
Ipswich, took up the subject, and seems at the time to have been un¬ 
acquainted with the researches of Fuchs and Kuhlmann. On opera¬ 
ting with the solution of silica he found that rain or even damp at 
once removed the film of hardened matter before the separation of 
silica was completed, and this seems to be the case with part of the 
Houses of Parliament submitted to the process of the French chemist. 
The buildings similarly operated on in France are decaying, shewing 
that a simple and superficial deposit of silica is insufficient. Mr. 
Ransome then after saturating the stone with the solution, followed it 
by a weak acid, so as to precipitate the silica in the substance, but 
found it was separated in a state in which it had no cementing or 
cohesive power. He then thought that if he could precipitate into the 
stone itself a compound possessed of great durability and hardness as 
well as cementing power, the difficulty would be overcome. Consider¬ 
ing that silicate of lime was the cause of the hardness of most cements 
and mortars, he produced that substance in this manner:—After the 
stone is cleaned it is washed over with a solution of silicate of soda, 
followed after a time by a solution of chloride of calcium. The result 
is that a decomposition takes place in the stone, attended by the pro= 
