On some of tin Combinations of Mercury. 53 



powder, put it into a shallow vessel ; then expose it to a heat 

 gradually raised till it cease to emit red vapours. 



Nitric acid is here directed to be added to the solution in 

 order that the protoxide of mercury may be saturated with acid, 

 from which a sufficient quantity of oxygen may be derived to 

 convert the mercury into peroxide, and thus the largest 

 quantity from the materials used be obtained. 



It deserves notice, that when calomel, red oxide of mercury, 

 and mercury, are rubbed tog-ether, moistened with water, they 

 combine and form a blue compound, a result which does not 

 appear strange if we adopt the old theory of the constitution of 

 muriatic salts, and consider this as a compound of muriatic 

 acid and protoxide of mercury, the protoxide being in excess 

 analogous to the combination of protoxide of mercury and nitric 

 acid; but if we adopt the new theory, that calomel is a com- 

 pound of chlorine and mercury, and does not contain oxygen, 

 the result appears rather singular, for, in this instance, we ob- 

 tain a compound altogether different from the other chlorides, in 

 this respect, that oxygen does enter into its composition. Ac- 

 cording to t'nis view it is a compound of chlorine, mercury, and 

 protoxide of mercury. 



On the Combinations of fixed Oil with Nitric Acid and the 

 Nitrates of Mercury. By Mr. Reid. 



[Head at thu South African Institution.] 



When nitric acid and hogslard, or any fixed oil, are exposed 

 together, and heat is applied, a quantity of gaseous fluid is 

 disengaged; the lard acquires a somewhat firmer consistence, 

 and assumes a yellow colour. If allowed to cool without 

 agitation, a yellow fluid subsides to tiie bottom, which, when 

 examined, is found to be weak nitric acid, holding in solution 

 a substance derived from the lard, which is precipitated when 

 the acid is neutralized. One ounce of nitric acid was com- 

 bined with six ounces of lard, the quantity of fluid amounted 

 to half an ounce, which neutralized five drachms of sub- 

 carboiiate of soda. By washing the compound with water an 

 additional quantity of acid was procured, which neutralized 

 four drachms of the same salt. Having combined one drachm 

 of nitric acid with subcarbonatc of soda, I found that it re- 

 quired four drachms for neutralization, therefore rather less than 

 two-thirds of the acid had combined with the lard. — The com- 

 pound of lard and nitric acid, when washed, did not effervesce 

 with alkaline carbonates, but alkalies and their subcarbonates 

 changed it to a reddish brown colour. 



