OF ZINC. . 357 



gelatinous state, which gradually assumed the 

 form of a light milk white deposite ; it continued 

 gelatinous and transparent (exactly like silica) 

 even after it had been collected on the filter, and 

 washed for some hours. When dried in the open 

 air it became an opaque white matter, like ena- 

 mel ; it was tasteless, insoluble in water, and did 

 not affect vegetable blues. 22 grains of this salt 

 being exposed to a red heat, lost 9 grains of its 

 weight ; hence its constituents are 



1 atom arsenic acid . 7-75 



1 atom oxide of zinc . 5'25 

 8 atoms water . . 9 -00 



22 



7. Chromate of zinc. This salt was obtained 

 by mixing solutions of sulphate of zinc and 

 chromate of potash in the atomic proportions. 

 The chromate of zinc precipitated in the state 

 of a fine yellow powder ; the supernatant liquid 

 being still yellow, was concentrated. It yielded 

 two distinct sets of crystals intimately mixed 

 with each other ; namely, bichromate of potash, 

 and sulphate of zinc tinged yellow by chromate 

 of potash. Chromate of zinc is nearly tasteless, 

 but it is soluble in water ; for the liquid with 

 which it was washed was yellow, and yielded, 

 when evaporated, chromate of zinc. Chromate 

 of zinc dried in the open air loses no weight 



Z3 



