472 Messrs. Wohlev and Liebig on 



the water, is agitated in a stoppered bottle with a little con- 

 centrated hydrochloric acid. The mixture generally solidifies 

 as a mass of fine needles, which may be se])arated from the 

 oil by washing with tether. In this manner hydrochlorate of 

 thialdine is obtained, from which pure thialdine may easily 

 be prepared by moistening the dry crystals with a concen- 

 trated solution of ammonia, and extracting the sepai'ated base 

 by means of aether. The aethereal solution yields by sponta- 

 neous evaporation crystals of pure thialdine. Addition of al- 

 cohol to the rethereal solution facilitates the crystallization 

 exceedingly ; the crystals become larger, more regular, and 

 perfectly transparent. 



Pure thialdine is heavier than water; its specific gravity is 

 1-191 at 18° C. ; it forms large, transparent, colourless, shining 

 crystals of the form of common gj^sum, possessing a highly 

 refracting power and a peculiar aromatic, but after some time 

 very disagreeable odour. The crystals fuse at 43° C. ; the 

 fused crystals solidify at 42° ; they are volatile at the tempe- 

 rature of the atmosphere without residue. Thialdine distils 

 with the vapour of water, but is decomposed when distilled 

 alone, a heavy oil of offensive odour passes over, solidifying 

 .only partly and after some time, whilst a brown, syrupy re- 

 sidue containing sulphur is left in the retort. Thialdine in 

 this respect resembles aldehydite of ammonia, which, though 

 volatile itself, cannot be exposed to a higher temperature with- 

 out decomposition. If a crystal of thialdine remains for several 

 hours in an atmosphere containing acid vapours, such as is the 

 case in the laboratory, a white envelope of fine silky needles 

 is found at a certain distance from the planes of the crystals. 



Thialdine is but little soluble in water ; it is soluble in al- 

 cohol, and much more so in aether ; when powdered it deli- 

 quesces at the common temperature in vapour of aether, or in 

 an atmosphere containing vapour of fether. 



An alcoholic solution of thialdine exhibits the following re- 

 actions : — 



With acetate of lead, at first no precipitate, but after some 

 time a yellow deposit appears, which soon becomes red and 

 finally black. 



Nitrate of silver causes a precipitate, which at first is white, 

 then yellow, afterwards black. 



With chloride of mercury a white pi'ccipitate is produced, 

 turning rapidly yellow. 



With bichloride of platinum a dingy, yellow precipitate is 

 thrown down after some time. 



Thialdine has no reaction on vegetable colours ; it is solu- 

 ble in all acids with which it combines, forming crystallizable 

 salts; the hydrochlorate and the nitrate are remarkable for 



