

1863.] 559 



of aniline is large. Thus peroxide of manganese or bichromate of 

 potash may be used in the same way as the red prussiate of potash 

 in the last experiment ; but these tests will not answer with less than 

 the -5- J-Qth of a grain of aniline. Lastly, a drop of a solution of 

 chloride of lime may be added to the acid liquid, and if the quantity 

 of aniline exceeds the T^th part of a grain it will cause a purple re- 

 action. 



9th. If the quantity of saline residue from the last operation is 

 large, and there is reason to believe that much ammonia is present, 

 this alkali must be got rid of, for it greatly interferes with the success 

 of the colour-experiments. The residue, therefore, is made moist 

 with water, and rubbed down with about twice its bulk of neutral 

 carbonate of soda. It is then exposed to the air for a short time 

 until the odour of ammonia has passed away. It is then treated with 

 strong alcohol, filtered, acidulated with dilute sulphuric acid, and 

 again evaporated. The aniline is now fit for the colour-experiments. 



There are no fallacies to these experiments ; for although, as I 

 have elsewhere shown, strychnia will give nearly the same colour- 

 reactions, yet in the first place this alkali is not volatile like aniline, 

 and will not therefore distil over as the latter does ; and in the next 

 place, while the best effects, in respect of colour, are developed with 

 dilute acid and aniline, strychnia requires the concentrated acid. 

 These differences are sufficient to prevent any embarrassment as 

 regards the two alkaloids. 



II. " On the Immunity enjoyed by the Stomach from being 

 digested by its own Secretion during Life." By 

 FREDERICK W. PAVY, M.D. Communicated by Dr. 

 SHARPEY, Sec. U.S. Received April 29, 1863. 



(Abstract.) 



The author stated that the opposition which his view on the above 

 subject received the evening of its announcement, in his former com- 

 munication read January 8, 1863, had induced him to perform a series 

 of additional experiments. As from these experiments some im- 

 portant confirmatory evidence was supplied, he deemed it desirable 

 to present a further communication to the Society on the subject. 

 He had again denuded the stomach of a patch of mucous mem- 



