150 Selections from Foreign Science. 



3. The liquid over the crystals, smelling strongly of hydrosul- 

 phuret of ammonia, when carefully distilled yields a brownish 

 liquid, with a yellow crystalline solid body consisting of the red- 

 dening salt and hydrosulphuret of ammonia, which when it amounts 

 to one-third leaves in the retort a colourless liquid, that upon 

 coolihg deposits long yellowish-white acicular crystals, these being 

 sulphur mixed with a little sulphuret of cyanogen. 



4. Decanting the liquor from the latter, ami re-distilling until 

 but little fluid is left, on cooling a spongy lamellated white substance 

 is deposited, and more of the same substance is dissolved in the 

 mother water. This substance dissolves readily in water, and oa 

 examination proved to be the sulphocyanate of ammonia of M. 

 Porret. 



5. If the liquid over the crystals in the flask, instead of being 

 distilled, be exposed to air, it loses colour, and in 24 or 30 hours 

 deposits voluminous crystals of sulphur mixed with a little hypo- 

 sulphate of ammonia, after which it contains the usual sulpho- 

 cyanate of ammonia. 



On the Reddening Salt, or Hydrocarhosulphuret of Ammonia. 



6. This salt is obtained in great quantity by using the sulphuret of 

 carbon and ammoniacal solution in the proportions before-men- 

 tioned, without the addition of the pure alcohol, and submitting 

 the mixture, when made, to temperatures from 39° to 43° Fahr., 

 but it then forms only a crystalline powder ; in about three 

 quarters of an hour the liquor is to be decanted, and the salt care- 

 fully washed with pure alcohol. 



7. The salt is at first of a light yellow colour, but reddens very 

 rapidly by contact with the air, becoming at the same time moist 

 and slowly evaporating ; it is principally the water of the air which 

 produces the change of colour. It is hardly possible to dry the 

 salt by bibulous paper v.ithout its becoming red, unless the alcohol 

 be removed from it previously by washing with ether ; and then by 

 compression in paper it may be dried, and will bear the contact of 

 air without alteration for five or six minutes. The salt is always 

 alkaline, but exposure to air increases the ammoniacal odour. 

 Water dissolves it entirely and readily, producing a brown-red 

 solution, unless very dilute, when it appears yellow. It is slightly 

 soluble in alcohol. 



8. Tlie solution in water treated with sulphuric or muriatic acid 

 loses its colour, liberates sulphuretted hydrogen, and after some 

 time becomes turbid as if from a little sulphur, but more acid 

 restores limpidity. No sulphurous odour was perceived even 

 when the solution was precipitated by a metallic salt before adding 

 the acid ; from which it results, that it contains no hyposulphurous 

 acid- It contains no carbonic acid, for salts of lime or baryta do 

 not precif(5late it. It produces a red precipitate with salts of lead ; 



