402 SALTS 



judging from the quantity of water actually 

 given out, I consider the constituents to be 



1 atom oxalic acid 4-5 



1 atom protoxide of mercury 26 

 1 atom water 1-125 



31-625 



Q, Pj'ototartrate of mercury. This salt preci- 

 pitates when tartrate of potash is mixed with so- 

 lution of protonitrate of mercury. The precipi- 

 tate, when it first falls, is snow white ; but in a 

 few minutes it blackens considerably, and, when 

 collected on the filter, washed and dried in the 

 open air, it is grey. It has scarcely any taste, 

 and does not appear soluble in water. 50 grains 

 of this salt were exposed in a platinum crucible 

 on the sand bath. No water was exhaled ; but 

 the salt blackened, in consequence of the decom- 

 position of the tartaric acid, and lost 1'9 grain of 

 its weight. From this experiment I consider 

 the salt as anhydrous, and composed of 



1 atom tartaric acid . 8-25 



1 atom protoxide of mercury 26 



34-25 



From the preceding list of the protosalts of mer- 

 cury it appears that, as far as their water of 

 crystallization is concerned, they bear a great re- 

 semblance to the salts of lead. Most of them 



