288 Notices of the Labours of Continental Chemists. 



and Robiquet's anhydrous pyrocitric acid. It is obtained by 

 distilling the itaconic acid, which gives water and citraconic 

 acid, which forms the inferior layer. On distilling afresh it 

 is obtained anhydrous : or it may be obtained by treating 

 the non-crystalline residue remaining from the itaconic acid 

 with acetate of lead, and decomposing the precipitate with 

 sulphuretted hydrogen. The acid is void of colour and smell, 

 has a strong acid acrid taste, sinks in water, does not mix with 

 it, but on longer contact soluble in it in every proportion ; 

 specific gravity = r'ii? at 14°; begins to volatilize at 90°, boils 

 at 212° cent.; heated further it leaves a carbonaceous residue. 

 Attracts moisture from the atmosphere, first becoming cry- 

 stalline, then deliquescing. The hydrate crystallizes in four- 

 sided prisms, which melt at 80°, and volatilize entirely a few 

 degrees higher ; soluble in water, alcohol and eether. On 

 being heated in a retort they first give off water, and then 

 anhydrous acid. The anhydrous acid = 54''12 C, 3*53 H, 

 42-35 O; the crystallized hydrate =46-62 C, 4-56 H, 48-82 O. 

 The atomic weight was determined from the anhydrous salts 

 of silver, lead and barytes, and was found to be 715-40; its 



formula, therefore, = C' H^ O^ the symbol Ct. Citraconic 

 aether is prepared in the same way as itaconic aether, with which 



it agrees in every respect; its formula C' H'^ O' = Ae O, Ct. 

 Anhydrous citraconic acid absorbs ammonia with violent 

 disengagement of heat, forming a yellow, ductile, transparent, 

 hygroscopic body, easily soluble in water and alcohol. This 

 anhydrous citraconate of ammonia = 2 C' H^ O' + N- H". 

 Dissolved in water and evaporated, small crystalline laminae of 

 the same salt are obtained as crystallizes from the acid solu- 

 tion by saturating direct with ammonia; formula = 2 C'H-'O^ 

 + N- H'5 + H- O. The neutral potash salt is easily soluble, 

 forms a pulverulent mass ; the acid salt crystallizes in easily 

 soluble laminee. Both soda salts easily soluble, non-crystal- 

 line. The acid salt of magnesia transparent, radiately cry- 

 stalline. The neutral lime salt is amorphous, easy of solu- 

 tion ; the acid salt crystallizes in prisms and laminae; formula 

 2 C^ H* O^ + Ca O, H- O + 3 Aq ; lose one atom of water 

 at 100°, three atoms at 120°, and at 140° blacken and evolve 

 acid. The neutral salt of barytes is white, crystalline, of dif- 

 ficult solution in cold water; the acid salt forms white silky 

 verrucous groups, loses no water at 100°, = 2 C' H* O' 

 + Ba O H- O -h Aq. The neutral salt of stroiitia is not 

 distinctly crystalline, efflorescent ; the acid salt forms large co- 

 lourless prisms, which become opakeatlOO°,andlose 26*19 per 

 cent, in weight ; at 120° gives off acid. The silver salt is only 



