1819.] Oxides and Salts of Mercury. 327 



is on this account that, by double decomposition, the resulting 

 mercurial salt is always below the point oi' saturation (44). 



Appendix, containing an Account of a new Mercurial Ointment. 



In an attempt, already detailed (11), to obtain black oxide of 

 mercury, I found that 60 gr. of metal, after 40 hours' trituration, 

 afforded but b' gr. of oxide. This fact, considered with the short 

 time that is bestowed on the extinction of the mercury in the 

 mercurial mills, excited my curiosity to examine the state of the 

 mercury in that mercurial ointment which is used in the cure of 

 the venereal disease, and of which the nature has been so much 

 disputed. 



1 kept four ounces troy of mercurial ointment, prepared in a 

 mill, about half a year before, at the temperature of 212° : it 

 separated into two strata. When cold, the upper stratum was 

 separated ; it was of a light-grey colour. The under stratum 

 was exposed to 212° on blotting paper, which soaked the 

 remaining lard. The very heavy residue was triturated with a 

 little magnesia, and it almost instantly afforded a quantity of 

 mercury weighing 495 gr. ; mere trituration with magnesia af- 

 forded 225 gr. additional. The earthy mass was put through a 

 variety of processes which gave a quantity of globules, they may 

 be rated at 60 gr. although 1 could not collect them all : a little 

 oxide also appeared. Thus out of 960 gr. of mercury which the 

 four ounces of ointment originally contained, there were reco- 

 vered 770, which leaves 190 gr. the quantity of mercury appa- 

 rently oxidized, or 47-i- to each ounce. But the quantity is really 

 much less. 



The grey ointment which constituted the upper stratum 

 appearing to contain oxide of mercury in a state of chemical 

 combination, and believing that the lower stratum being metallic 

 mercury could have no effect on the animal economy, when 

 introduced into the circulation, I conceived that the medicinal 

 effects of mercurial ointment must depend on the small quantity 

 of oxide with which the fat is chemically combined. 1, there- 

 fore, determined to tiy if this grey ointment would affect the 

 human body in the same maimer as the common mercurial 

 ointment. I provided three females whose situation required 

 the use of mercury. Each rubbed in a drachm every night. 

 One was affected by the third rubbing, and the fourth put her 

 under ptyalism. Another after rubbing three times was so 

 salivated that she spit two quarts in the 24 hours ; and this in a 

 less degree was kept up for 10 days. The third was not affected 

 until she rubbed six times, and then not considerably. They 

 were all at length recovered. 



Finding this ointment so very active, I conceived that by 

 forming a chemical combination between fat and oxide of mer- 

 cury in very small quantity, the same result might be ob- 

 tained. ], therefore, kept lard and black oxide of mercury at 



