is 15.] Oifla's Treatise on Poisons. 38f 



The effect of cantliaiides when taken into the stomach in_ any 

 quantity is well known. It produces a most furious satyriasis, 

 which usually tcnniiiates in gangrene and death. No antidote 

 against this formidable poison has been hitherto discovered. 



All the preparations of lead are poisonous ; but those most likely 

 to be taken into tlie stomach are the oxides of lead, white lead, 

 litharge, and sugar of lead. The water near lead mines, in which 

 the calcna is washed, is usually injurious to the health, in conse- 

 quence of particles of that substance which it holds in suspension. 

 The fumes of lead prove no less injurious to those who are ex- 

 posed to them. 



Lead shows its deleterious effects in those who are exposed to its 

 action ; but slowly. Obstinate costivcness and violent colics, known 

 by the name of colica pictonum, first attack the patient. This is 

 followed by paralysis and death. It appears from the experiments 

 of M. Orfila, that sulphate of magnesia acts as an antidote against 

 acetate of lead. An insoluble sulphate of lead is formed, which 

 does not injure the animal economy, and the acetate of magnesia 

 acts merely as a purgative. The common method of treating per- 

 sons poisoned by lead is by a course of purgative and emetic medi- 

 cines, which seldom fail to cure the patient. 



In an appendix JVI. Orfila gives us a set of experiments on iodine, 

 introduced into tlie stomach of animals. In small quantities it 

 acts as an exciter. When administered to the amount of about 

 half an ounce it occasions death, if the animal be prevented from 

 vomiting, gradually corroding the stomach and intestines. _ When 

 taken in larger quantities it destroys life even though the animal be 

 allowed to vomit. 



In another appendix M. Orfila shows by experiment, that char- 

 coal powder is not an antidote against corrosive sublimate and white 

 4.)xide of arsenic, as had been advanced by M. Bertrand. 



Article XII. 



proceedings of Philosophical Societies, 



UOYAL SOCIKTY. 



On Thursday, the Gth of April, a paper by Mr. Knox was read, 

 on the coloured rings formed when a flat plate of glass is pressed 

 against a convex lens, Mr. Knox conceives that the reason why 

 neither Sir Isaac Newton, Dr. Herschell, nor any other philosopher, 

 was able to give a satisfactory explanation of these coloured rings, 

 was, ih»t they were not acquainted with all the phenomena. He 

 made his experiments according to the method pointed out by Dr. 

 Herschell in liis paper on the subject published in the Phil. Trans, 

 for ltt04. Mr. Kuox described a great many new phenomena 



2 B 2 



