Dr. Guy, on Microscopic Sublimates, 



11 



several reactions of a solution of the muriate of strychnine 

 and carbazotic acid, confirmed by like reactions with the 

 acetate, nitrate, sulphate, and phos- 

 phate of strychnine (three with each), -^'S- ^• 

 namely, groups of curved crystals 

 waving in the liquid like tufts of 

 grass. Figure 3 shows these curved 

 crystals as they appeared in the dried 

 spot resulting from the reaction of 

 carbazotic acid with a solution of 

 the phosphate of strychnine. It is 

 of these tufts of curved crystals and 

 layers of " millfoil " that I am now 

 to speak as developed, when a solution of carbazotic acid is 

 dropped upon the sublimate of strychnine. 



This reaction is not instantaneous, but very speedy. Some- 

 times, however, the transparent solution thickens as it 

 touches the spot, just as, when added to a solution of a salt 

 of strychnine, a dense precipitate is formed. But the reac- 

 tion commonly shows itself, after the lapse of a minute or 

 two, in the development of circular, greenish-yellow spots, 

 in the centre of which a still darker spot appears. These 

 spots grow in size, and soon display an arborescent form ; 

 and still growing, often coalesce with neighbouring spots to 

 form a large continuous layer, or they remain distinct. In 

 these spots themselves, and often as separate formations, that 

 feature of the hook or claw to which I wish specially to in- 

 vite attention develops itself, sometimes springing up into 

 the liquid, sometimes lying flat upon the glass, and often 

 forming a delicate and characteristic fringe to the yellow 

 carpet into which the coalesced spots have formed them- 

 selves. In the dry spot, the coarse prisms, groups of needles, 

 and long colourless plates, or plates with markings like those 

 of the common razor-shell of the seashore, all belonging to 

 the reagent, intrude themselves, and tend to confuse the 

 bright yellow patterns, like delicate sea- weeds, and the bun- 

 dles of hooks which result from the union of the carbazotic 

 acid with strychnine. Some of these curved forms, in the 

 case of the sublimate, and several in the case of the solutions 

 of the salts of strychnine, are delicately feathered. Some- 

 times, though rarely, and then in the case of the coarser 

 sublimates, these peculiar hooks or claws are absent ; but 

 the distinct arborescent forms, forming and growing under 

 the eye, are always present, and, as I have reason to believe, 

 are also characteristic. Sometimes, again, when the subli- 

 mate of strychnine consists of well-marked crystalline forms, 



