6 Dr. Guy, on Microscopic Sublimates. 



marked sublimate of strychnine, and a single black speck of 

 carbon, as a residue. 



The same sublimate, with the same residue, may be ob- 

 tained from strychnine in powder, and from strychnine as 

 deposited from its solutions ; but, in this last case, the alka- 

 loid does not melt, though it leaves a speckled black stain. 



I will now describe the sublimates of strychnine, with 

 these ten sublimates at my side, with notes of the results of 

 former experiments at hand, and assisted by the recollection 

 of some hundreds of specimens. 



Strychnine yields three kinds of sublimate : a sublimate 

 consisting of a white spot or spots ; a sublimate consisting of 

 colourless drops, or a colourless waving pattern j and a sub- 

 limate consisting of the same drops, or waving lines, more or 

 less discoloured by smoke. All the first sublimates of the 

 series have the first form; the second variety shows itself 

 when the alkaloid is nearly exhausted ; the third when the 

 alkaloid, being also nearly exhausted, is submitted to excess 

 of heat. Of the watered and smoked varieties I will merely 

 observe that, though not characteristic in themselves, they 

 may behave quite characteristically with certain reagents, of 

 which I shall speak presently, and that, therefore, they 

 ought not to be rejected. 



The sublimates which belong to the first class consist of a 

 single white spot, often, though not 

 ^^' always, circular, and often surrounded 



by an outer circle of mist ; or of several 

 circular spots, distinct or coalesced. Fig. 

 1 shows a spot of this compound form of 

 natural size, as seen by a good transmit- 

 ted light. These white spots or sublimates 

 present, under the microscope, many 

 forms. I will specify those with which I 

 am most familiar. 



1. Smooth uniform layer, bordered with a sort of fringe or 

 lacework. 



2. The same, but with the layer made up of minute disks. 



3. The same, but sprinkled with a fine black dust. 



4. The same, but with black feathers, fern-leaves, or furze- 

 bushes, or with groups of feathers or leaves, projecting from 

 the layer or crust. 



5. Sublimate of varying thickness, white or opalescent, 

 consisting of parallel waving or curved lines, conchoidal pat- 

 terns, straight twigs radiating from a point, fine trellis or 

 lattice-work, and various arborescent forms. 



6. Confused mixture of square or oblonj; patches, finely 



