in Reply to Dr. Bostock. 291 



A lady had a wound on the breast in a healing state; a promi- 

 nent speck of a black colour suddenly made its appearance on the 

 surface, it was tender beyond expression to the touch. Next day 

 it disappeared, and the tenderness was gone. The speck must 

 have been this jelly coagalated upon the termination of a nerve, 

 and therefore the impression made by touching it was communi- 

 cated to the nerve ; but when it was absorbed, the nerve received 

 a coating of coagulable lymph, and there was no more pain. 



Mr. Hunter's comprehensive mind grasped at the idea of the 

 existence of something of this kind, although he had not arrived at 

 a knowledge of the substance employed to produce the effect. He 

 said, that so wonderful was the connexion between the brain and 

 every structure of the body, that it was to be explained in no other 

 way, than by considering that the materia mtce was every where 

 in one of two forms ; collected into one mass in the brain, which he 

 called coacervata; and diffused through the body, which he called 

 diffusa ; and the nerves communicated between them. 



From Mr. Bauer's microscopical examinations of the medullary 

 structure of the brain, the variety in the size of the globules, and 

 in the consistence of the uniting medium, it becomes evident that 

 very different functions are performed by these various structures. 



Art. VII Facts towards the Chemical History of Mercury. 



§ I. Of the Oxides of Mercury. 

 Some valuable information respecting the oxides and sulphurets 

 of Mercury has been published by M. Guibourt, in the Journal de 

 Pharmacia, of the year 1816 ; but we cannot agree with his conclu- 

 sion as to the impossibility of obtaining an insulated protoxide, and 

 an insulated protosulphuret of that metal ; at least, if we under- 

 stand him rightly, he considers those compounds as mixtures of 

 metallic mercury with the peroxide and bisulphuret respectively, and 

 this, because they are so easily resolved by heat, and even by tritura- 

 tion, into running mercury and peroxide, and running mercury and 

 bisulphuret. But we do not reject iodide of nitrogen, or fulminating 



