226 Biography of Johann Nepomuk von Fuchs. 
vineed himself by numerous experiments that lime is =i 
of uniting in the wet way with silica and its compounds, e 
with such as already contain lime. The completest proof of “this 
he found in the facts that certain insoluble silicates, and silica 
‘itself “in a certain degree of coherence,” gelatinize. with acids 
after they have been mixed for some time with lime ina moist 
- state, and that these mixtures also increase more and more in 
hardness and solidity. These instructive experiments were in- 
stituted on quartz, opal, artificially prepared silica, and its gela- 
tinous hydrate, feldspar, porcelain earth, clay, garnet, prehnite, 
analcime, Hoga ite, &. He con firmed the result which he 
moors, as material for cement, _ proposed that it be wo 
by buming marl, using the tu: ’ 
. essay may “be aN as a continuation of the paper 
on Lime ail Mortar, and sums up clearly the experimen 
sults, with this conclusion ; that the hardening of hydraulic ce- 
ment depends essentially upon a chemical union of silica with 
lime, which gradually takes place in the wet.way. .Ace 
there can be no hydrauli¢ cement without hen and. fu 
there is Bee a, a hydrated silicate or zeolitic compo’ 
discovered that but very few natural silicates (some ¥ came pro: 
ducts excepted) are so constituted thes lime acts on them direetly 
in the wet a Way, they mostly require to be burned, some of t 
indeed must be burned with a little aan before they are 
on. What "Fuchs had said in his academical oration with 
to the relations between chemistry and mineralogy, he fe 
monstrated practically. He could hardly have been so success 
ful in this research had he not been acquainted with both these 
ces, since the latter faanishee the materials for the solution 
a ie problems that occurred to him. - These results exp 
po Tre: 
Letters on Chemistry,” as follows: Fithese inte interesting facts were 
ist OEE y Fuc mie a Munich ; iaad $d oo not only int to i 
intimate knowledge of the re ab properties of 
hydraalie cements, but, what is ra mp important, they ex} ise 
the effects of caustic lime upon the soil, and ar the gricaltur 
