397 



this indeed appears but a feeble tribute of respect to the services 

 which he has rendered to the science of mineralogy. 



Since the crystallization of certain mineral substances, in which 

 nothing but earths has been discovered, has appeared problematical 

 to many persons, and has led to the supposition of the existence of 

 unknown acids in their composition, Mr. Smithson endeavours to 

 explain this difficulty, by suggesting that quartz itself may be con- 

 sidered as an acid, to which class of bodies it has analogous quali- 

 ties : we shall then have a numerous class of silicates, both simple 

 and compound ; and zeolite will belong to the latter, and may be 

 regarded as a hydrated silicate of alumina. 



Experiments and Observations on the different Modes in which Death 

 is produced by certain vegetable Poisons. By B. C. Brodie, Esq. 

 F.R.S. Communicated by the Society for promoting the Knowledge 

 of Animal Chemistry. Read February 21, 1811. [Phil. Trans. 

 1811, p. 178.] 



The substances selected for these experiments are vegetable poisons 

 only ; and they were chosen of the most active kind, that the exact 

 nature of their effects might be more readily discerned. The prin- 

 cipal object of the experiments is to determine on which of the vital 

 organs the influence of each poison is exerted, and through what 

 medium the organ becomes affected. The first series of experiments 

 relates to the effects of internal application to the tongue and ali- 

 mentary canal, and the second to the consequences of application to 

 external wounds. 



When proof spirit was given to a rabbit .in sufficient quantity to kill 

 it, the heart was observed to continue in action after apparent death. 



The same observation was made respecting the heart of a cat, 

 killed by injecting the root of aconite into the rectum. 



When the oil distilled from bitter almonds was employed, although 

 no more than a single drop had been given to a cat, she died in five 

 minutes. Two drops of the same oil injected into the rectum of an- 

 other cat, killed it also in five minutes. And the heart, in each in- 

 stance, continued acting after apparent death. 



Distilled oil of tobacco exerted nearly the same energy as the 

 distilled oil of bitter almonds, and apparently in the same way, as 

 the heart was observed to contract after apparent death. 



From this circumstance, Mr. Brodie inferred that these poisons 

 exert their primary influence on the brain, and that death ensues in 

 consequence of the suspension of respiration, which is dependent on 

 the brain. 



When an infusion of tobacco was made use of instead of the em- 

 pyreumatic oil, and injected into the rectum, the effects were different 

 from any of the preceding, as the heart continued to contract, and 

 was uniformly found in a state of extreme distension. Mr. Brodie 

 is, however, of opinion, that the heart was not directly affected, but 

 through the medium of the nervous system. For when the same 



