230 CONJUGATED ACIDS. 



when heated, dissolves, and burns with a bright but smoky 

 flame. 



Hyocholate of ammonia, H 4 NO.C 54 H 43 NO 10 , is a white crys- 

 talline powder. Its solutions become turbid on boiling, and 

 assume an acid reaction. It may be dried over sulphuric acid 

 without loss of ammonia. 



Hyocholate of baryta, BaO.C 54 H 43 NO 10 , is a gelatinous sub- 

 stance, freely soluble in spirit, moderately soluble in hot water, 

 and slightly so in cold water. 



Hyocholate of lime, CaO.C 54 H 43 NO 10 , is white, amorphous, 

 and rather more soluble in water than the baryta-salt ; it is preci- 

 pitated from its spirituous solution by water and by carbonic 

 acid. 



Hyocholate of lead is a white powder, which neither cakes when 

 boiled with water nor when dried ; it is slightly soluble in water, 

 but freely in spirit, from which it (like all the other salts of this 

 acid) is precipitated by ether. Red litmus is turned blue by the 

 alcoholic solution. 



Hyocholate of silver, AgO.C 54 H 43 NO 10 , occurs as a gelatinous 

 precipitate, which, on boiling^ becomes flocculent; it dissolves 

 freely in spirit, slightly in cold, but somewhat more easily in 

 hot water. 



Preparation. The precipitate caused by the addition of a solu- 

 tion of sulphate of soda to fresh swine's bile is dissolved in abso- 

 lute alcohol, decolorised by a little animal charcoal, and the soda- 

 salt of the acid precipitated by ether from the alcoholic solution ; 

 this is decomposed by dilute sulphuric acid, and the precipitate is 

 dissolved in alcohol, from which the hyocholic acid is thrown down 

 by the addition of water. 



Tests. It is only with glycocholic and choloidic acids that this 

 acid can possibly be confounded. From the former it may easily 

 be distinguished by the circumstance that neither it nor its salts can 

 be obtained in a crystalline state by the addition of ether to alco- 

 holic solutions. It is, however, not so readily distinguishable from 

 the latter, because, without an elementary analysis, it is impos- 

 sible to determine its nitrogen; and because, further, when treated 

 with concentrated hydrochloric acid it yields too little glycine to be 

 recognised with certainty, unless, indeed, we have a very large 

 supply of the material to be investigated. The fact that hyocho- 

 late of lead neither cakes when dried nor when boiled with water, 

 while the opposite is singularly the case with the glycocholate, 

 affords a tolerably characteristic test. Other differences are for 



