1878. ] ATT | Marshall. 
171° C. and perfectly identical with the monochlorsalicylic acid. The 
graphic formula of the latter would be represented by the following : 
COOH. 
OH. 
Me 
COOH. COOH. 
OH. 
Benzoic Acid. COGH. Orthoxybenzoic Acid 
(Salicylic Acid.) 
OH. 
Me 
Metachlororthoxybenzoic Acid. 
Cahouwrs in 1845 described a similar acid, ‘‘Acide monochlorosalicylique’’ 
(Ann. Chim. Phys. 13, 106), but never obtained it in a pure condition. 
The method I pursued to secure the acid for my investigations was the 
following: A weighed amount of the purest salicylic acid that could be 
obtained (Melting at 155° C.) was brought into a capacious flask, and a 
rather large quantity of concentrated acetic acid added. Into this mixture 
a calculated amount of dry chlorine gas was conducted. The heat gen- 
erated by the reaction soon caused the solution of the salicylic acid. The 
liquid gradually acquired a yellowish-brown color. When the calculated 
amount of chlorine had been introduced, water was added in large excess 
and the solution allowed to stand several hours before filtering off the acid 
that had separated out in large white flocculent masses. After thoroughly 
washing the acid with cold water, it was boiled with a large quantity of 
barium carbonate and water. The liquid was filtered from the excess of 
the latter salt, evaporated and allowed to stand over night. Upon exami- 
nation crystals of barium dichlorsalicylate were usually discovered. The 
mother liquid poured off.from these and further concentrated yielded the 
barium salt of the monochlor acid. This salt I invariably recrystallized 
several times, and then added dilute hydrochloric acid to its aqueous solu- 
tion which precipitated the acid in perfectly white flocculent masses. 
The acid was recrystallized several times from water separating out from 
this menstruum in long colorless needles which fused at 172° C. In warm 
water the acid is readily soluble. 
