MINUTE DIVISION OF MERCURY. 
245 
From this chronological series of contradictory statements, 
it would appear that our knowledge of the subject goes very 
little further than this — that mercury, by oxidation, or by 
division, acquires the power of absorption by the system, 
a fact noted by Quincy in the year 1753. 
The theory of metallic division, which was discarded in 
the year 1S15, is now revived, and is ably supported ; but, 
notwithstanding the numerous investigations which have been 
made in order to establish the truth, we cannot consider the 
question entirely settled, while some of our first authorities 
give us their opinions as probabilities. In a scientific point 
of view, the subject is interesting ; and it is rendered intricate 
by the manner in which this metal passes from one state of 
oxidation to another, by exposure to light, heat, and other 
agencies, and the fallacies which may hence arise during our 
manipulations. 
The cinereous or protoxide of mercury spontaneously 
undergoes a partial decomposition, resolving itself into a mix- 
ture of protoxide, binoxide, and metallic mercury. Globules 
may occasionally be observed in a bottle containing this pre- 
paration, after it has been kept for some time exposed to 
light, and they have also been detected in black wash. The 
binoxide is less liable to decomposition, but it appears that the 
affinity between mercury and oxygen in a low state of oxida- 
tion is very slight. Some of the phenomena which are ob- 
servable in experiments on this substance, would lead us to 
suspect the existence of a compound containing a smaller pro- 
portion of oxygen than the protoxide, probably a hydrated sub- 
oxide, but further investigation is required in order to sub- 
stantiate this theory. 
But this consideration which more particularly concerns 
the Pharmaceutical Chemist, is the amount of importance 
attached to oxidation in giving medicinal activity to mercury, 
and the practical application of the knowledge we possess to 
the manipulations of that metal. 
In mixing hydrarg. cum creta with extracturn rhei, globules 
of mercury are frequently seen in the mortar. This is inva- 
