Intelligence and Miscellaneous Articles. 77 



and whitish. This suhstance is usually of a brightish oil-green 

 colour, passing to olive-green ; it has a characteristic pearly and 

 silky lustre. Its density is 2*219. M. Delesse found it to consist of — 



Silica 41-58 



Alumina 042 



Oxide of iron 1'69 



Magnesia 42-61 



Water 1370 



10000 



The chemical composition of chrysotil is identical with that of the 

 picrolite of Stromeyer, with the different noble serpentines recently 

 analysed by M. Lychnell, and especially with the crystallized ser- 

 pentine of Snarum. The density of chrysotil is, however, less than 

 that of serpentine, which seems to indicate that it is a dimorphous 

 variety of serpentine. — Ibid. 



ON CHLORIDE OF GOLD AS A TEST OF ORGANIC MATTER IN 

 COMMON WATER. 



M. A. Dupasquier states, that after having found by numerous 

 experiments that nitrate of silver was an uncertain test of the pre- 

 sence of organic matter in waters, he tried other processes, and at 

 last found that chloride of gold might be successfully employed. 

 The method of employing it is to put from twenty-five to thirty 

 grammes of the water to be examined into a flask, and to add to it 

 sufficient solution of perfectly neutral chloride of gold to render it 

 slightly yellow, and afterwards to boil it. If the water contains only 

 the usual quantity of organic matter found in drinkable waters, it 

 retains its yellow colour ; if, on the contrary, it contains an undue 

 proportion of organic matter, it immediately becomes brown, then 

 assumes a violet or bluish tint, which indicates the decomposition of 

 the chloride of gold by the organic matter. By continuing the ebul- 

 lition, the violet or bluish tint becomes deeper, if the proportion of 

 organic matter be considerable ; but if the liquid becomes slightly 

 brownish or greenish, it is sufficient to prove that the water contains 

 an unusual quantity of organic matter. The solution of gold must 

 contain no excess of hydrochloric acid, as that would prevent the 

 decomposing action of the organic matter. 



It sometimes occurs, when the ebullition has been long continued, 

 that the solution is rendered colourless by the precipitation of oxide 

 of gold by the carbonate of lime in the water, unless the chloride 

 has been used slightly in excess ; and when it is so, the yellow tint 

 may be modified by the liquid being rendered slightly turbid. To 

 distinguish these effects from those of the decomposing reaction 

 produced by the organic matter, a drop or two of hydrochloric acid 

 is to be added, which will immediately dissolve the oxide of gold, 

 and the liquid will assume its original appearance, unless the salt of 

 gold has been decomposed by the organic matter. When, however, 

 the chloride has been once reduced to the metallic state bv the or- 



