242 Dr THOMSON'S Experiments on the 



water into the solution, the gallactin precipitates, apparently 

 little altered except in colour. But if we cautiously evaporate 

 the nitric acid solution to dryness, a yellow, brittle, bitter-tasted 

 substance remains, which is soluble both in water and in alcohol. 



The aqueous solution of this substance is not affected by 

 prussiate of potash or infusion of nut-galls ; but with nitrate of 

 lead, or nitrate of mercury, it gives a white precipitate. The 

 precipitate with the former is scanty, with the latter abundant. 



The alcoholic solution is yellow and very bitter tasted. Wa- 

 ter occasions a precipitate, which, however, is re-dissolved on agi- 

 tating the liquid. It is precipitated by nitrate of lead, nitrate 

 of mercury, sulphate of zinc, sulphate of manganese, muriate of 

 barytes, muriate of strontian, muriate of lime, and muriate of 

 magnesia. 



3. When gallactin is put into sulphuric acid, the liquid as- 

 sumes a fine brownish-red colour, which gradually deepens. The 

 acid appears green by reflected light, and deep brownish-red by 

 transmitted light. The gallactin becomes soft and dark brown. 

 When sulphuric acid is heated in contact with gallactin, it frothes 

 and assumes a black colour, sulphurous acid being given out 

 abundantly. 



4. When gallactin is heated in water, it does not float on the 

 top of the liquid, under the form of a transparent oil, as is the 

 case with wax ; but it imbibes a great deal of water, and assumes 

 the form of a white, opaque, viscid matter, not unlike the gluten 

 of wheat in its appearance and adhesive nature, but much more 

 fluid. 



Some of these characters approach those of the volatile oils ; 

 but gallactin is devoid of smell, and likewise of taste, and the 

 temperature at which it boils is certainly not lower than 600. 

 By my thermometer it was 640. In combustibility and consis- 

 tence it resembles wax ; but the action of alkalies, nitric acid, 



