Page:Experimental researches in chemistry and.djvu/18

1816.] The precipitate, when well washed and dried, weighed 0&middot;95 of a grain. It was soluble in sulphuric acid, and possessed the properties of alumina.

Diluted sulphuric acid was added to the solid matter not acted upon by the potash; the whole boiled for some time, and then filtered. The sulphate of lime obtained weighed, after being heated red, 136 grains, which, estimating the lime at 43 per cent., is equivalent to 58&middot;48 grains of lime.

The sulphuric solution was precipitated by ammonia, and two grains of oxide of iron were obtained.

Supposing the quantity of water in every part of the piece first taken to be uniform, it would follow that the 188 grains contained 117&middot;05 of water; so that 70&middot;95 was the quantity of dry matter acted upon. The results were—

The loss is therefore rather more than two grains, which may, perhaps, actually have taken place, and the difference may have been derived from the unequal diffusion of water throughout the piece.

Supposing 100 parts of the specimen to have been taken, the analysis will stand thus:—

It is perhaps worthy of observation, that during the solution of the substance in muriatic acid, a part only of the silica separated; the greater part remained in solution until heat was applied, when it gelatinized, as in the case where it is separated by an acid and heat from its combination with alkali.