300 ANNUAL OF SCIENTIFIC DISCOVERY. 



portion of silica, the result being a silicatization of the magnesia through 

 the intervention of the alkali. 



With soluble silica (as prepared by igniting the silica from the decom- 

 position of an alkaline silicate), this reaction is very rapid, and even when 

 pulverized quartz is boiled for several hours with carbonates of soda and 

 magnesia, a large amount of magnesian silicate is formed. If we substi- 

 tute proto-carbonate of iron and boil it with soluble silica and carbonate 

 of soda, there is formed a hydrous silicate of the protoxyd permanent in the 

 air. 



It will be apparent that by virtue of the power of earthy carbonates 

 to decompose an alkaline silicate, and that of the regenerated carbonate 

 of soda to dissolve silica even in the form of quartz, a small amount of 

 alkali may effect the combination of a great quantity of silica with earthy 

 bases. 



Suppose a solution of alkaline silicate, which will never be wanting 

 among sediments where felspar exists, to be diffused through a mixture 

 of siliceous matter and earthy carbonate, and we have with a tempera- 

 ture of 212 F. and perhaps less, all the conditions necessary for the con- 

 version of the sedimentary mass into pyroxenite, diallage, serpentine, talc, 

 rhodonite, all of which constitute beds in our metamorphic strata. Add to 

 the above the presence of aluminous matter and you have the elements 

 of chlorite, garnet and epidote. We have here the explanation of the 

 metamorphism of the Silurian strata of the Green Mountain range, and 

 I believe of rock metamorphism in general. 



OBSERVATIONS ON THE SOLUBILITY OF SALTS. 



At the Dublin meeting of the British Association, Professor Sullivan 

 read a paper "On the Solubility of Salts at a Temperature above 100 de- 

 grees Centigrade, and on the Action of Saline Solution upon Silicates un- 

 der the Influence of Heat and Pressure." The chief point referred to was 

 the fact, as already obsei-vcd by Couse, that sulphate of lime is almost 

 totally insoluble in water at a temperature of 150 degrees Cent. At tem- 

 peratures above 100 degrees Cent., the salt separating is not the ordinary 

 salt with tw r o equivalents of hydrated water, but the one with the two 

 equivalents of sulphate of lime and one of water. At a temperature of 

 160 to 170 degrees Cent., the sulphate of lime is deposited in the anhy- 

 drous condition a fact of considerable importance in a geological point 

 of view, as showing that anhidrate may be formed even in water at tem- 

 perature, which may be readily obtainable in deep seas. He also found 

 Labrador felspar exposed in a solution of common salt to a temperature 

 of 1 50 to 200 degrees for a considerable time is decomposed to some extent, 

 chloride of calcium being found in the solution. 



VON FUCHS, ON THE FORMATION OF THE PRIMITIVE ROCKS. 



A biographical sketch of the life of Von Fuchs in Silliman's Journal, thus 

 notices the views of this eminent chemist, in regard to the formation of the 



