Kolbe and Lautemann on Salicylic Acid and its Homologues. 383 



treating salicylate of soda with pentachloride of phosphorus. 

 The authors name it chloride of chlorsalyle. When it is treated 

 with water, an acid is obtained which has the composition of 

 chlorobenzoic acid, C' 4 H 5 C10 4 , and was formerly thought to 

 be that acid until Limpricht and Uslar showed that this was not 

 the case. Kolbe and Lautemann name the acid chlorsalylic acid. 

 It differs from chlorobenzoic acid in having a different crystalline 

 form, and in being about three times as soluble in water as that 

 acid. The two acids also differ in their melting-point. Unlike 

 salicylic acid, chlorsalylic acid gives no purple colour with per- 

 chloride of iron, but, like chlorobenzoic acid, a yellow precipitate. 

 The acids likewise differ in their deportment towards sodium- 

 amalgam : chlorobenzoic acid is attacked with great difficulty, 

 but chlorsalylic acid is readily converted into a new acid. 



To obtain this acid, a quantity of sodium-amalgam was added 

 to a concentrated aqueous solution of chlorsalylic acid, and the 

 mixture ultimately heated to boiling for some time ; the mercury 

 having been separated, the filtrate was treated with hydrochloric 

 acid, by which a crystalline magma was separated. This, on 

 appropriate purification, was obtained in beautiful crystalline 

 needles. 



This new acid the authors name salylic acid: it has the for- 

 mula C 14 H 6 O 4 . It is isomeric with benzoic acid, and stands to 

 salicylic acid in the same relation as propionic acid does to lactic 

 acid*. It crystallizes in small, microscopic needles, the form of 

 which differs from that of benzoic acid. It is about three times 

 as soluble as benzoic acid ; it is more volatile, and, unlike that 

 acid, it melts in hot water to a clear oil before it dissolves. The 

 salts, of which many were examined, also differ considerably 

 from those of benzoic acid. 



In these investigations there was frequent occasion to deter- 

 mine the solubility of the different acids. This was effected by 

 preparing a solution of the acid of such a strength that, on cool- 

 ing, very little crystallized out. This was cooled to 0° for several 

 hours and filtered. A measured quantity was then determined 

 by means of a standard alkaline solution. 



Chloride of Salyletrichloride, C 14 H 4 C1 4 . — This is the oil left 

 after the crude product of the action of pentachloride of phos- 

 phorus on salicylic acid has been treated with water. It forms 

 a yellowish oil, which, when dried over chloride of calcium, distils 

 over colourless, and solidifies to a brilliant mass of crystals. Its 

 specific gravity is 1*51 ; it melts at 30°, and boils at 265°. It 

 has a strong tendency to crystallize. Heated in a closed tube 

 with water, it is converted into hydrochloric and chlorsalylic 

 acids. 



* Phil. Mag, vol. xix. p. 384. 



