408 BRITISH PHARMACEUTICAL CONFERENCE, NORWICH. 



1868. the tests already in use merits attention. Dr. Guy may, there- 

 fore, well deserve our thanks for the exactitude and unwearied 

 patience with which he has performed an immense number of 



Sublimation of experiments on the sublimation of the alkaloids, a process first 

 Alkaloids. ^ rou ght to the attention of the chemists in 1864, by Dr. Helwig, 

 of Mayence. Dr. Guy has arrived at the conclusion that this 

 method of subliming substances in minute quantities on flat 

 surfaces of glass, in order to their complete examination by the 

 microscope, a method first recommended for arsenious acid and 

 corrosive sublimate, may be advantageously extended to the 

 alkaloids and analogous active principles that characteristic 

 results are readily afforded, with very minute quantities, such 

 as a thousandth of a grain of strychnine, or even less that the 

 results obtained by sublimation in the case of the alkaloids 

 and analogous active principles are not more subject to failure 

 than those of other tests ; in fact, that several of the reactions 

 are remarkable for delicacy, constancy, and characteristic 

 appearances. 



Closely connected with this subject is the question of the 

 temperature which must be reached in order that any par- 

 ticular alkaloid may assume a gaseous form, or, in other words, 

 that it may sublime. Dr. Guy, impressed with the unsatis- 

 factory statements made in toxicological works, and the some- 

 what rough modes of procedure adopted in order to test the 

 volatility of such bodies, has applied himself to devise a more 

 exact method, to the results of which, communicated in the 

 Pharmaceutical Journal of February last, I must refer you. 



Another excellent observer, who has also studied this depart- 

 ment of chemistry, is Mr. H. J. Waddington, whose paper on 



Micro-Sublim- micro-sublimation elicited, when read, some interesting remarks 

 atioD. f rom D r Q UVj D r Attfield, and others. In common with Dr. 

 Guy, Mr. Waddington had experienced the defects of the common 

 method of subliming in a glass tube over a naked flame sub- 

 stances so easily decomposed as vegetable alkaloids, a method 

 which has given rise to such statements as that a body is partly 

 sublimed and partly decomposed, which seemed to imply that 

 the substance exposed to heat is not homogeneous, but that one 



