ON OXALIC ACID. gg 



Thus it appears, that iheve are two oxalates of strontian, Two species. 



the (irst obtained by saturating oxalic acid with strontian .^"^^''''^J '^'■'"; 

 ' . , '^ _ ble tile base of 



water, the second by mixino^ together oxalate of ammonia the other. 



and muriate of strontian. It is remarkable, that the first 



contains just double the proportion of base contained in the 



second. 



TIL Decomposition of the Oxalates. 



1. When oxalic acid, in the state of crystals, is exposed Crystallized 

 to heat, it is only partially acted upon, a considerable por- ^"^'1 '" 'f^*^ 

 tion escaping without alteration ; but when an alkaline or in oxalates de- 

 earthy oxalate is heated, the acid remains fixed, till it un- ^"^JJ''"^^'^ ^^ 

 dergoes complete decomposition. The new snbstances into 



■which the acid is converted, as far as my experience goes, 



are always the same, what oxalate soever we employ. They 



are five in number ; namely, ivafer, carbonic acicU carbonic i>rodLicts 



oxide, carburetled hldrogen, and charcoal. 



2. The water is never quite pure. Though no sensible -at 

 portion of oil can be perceived in it, yet it has always the 

 peculiar smell of the water obtained during the distillation 

 of wood; a smell which is usually ascribed to oil. It com- 

 monly shows traces of the presence of ammonia, changing 

 vegetable blues to green, and smoking when brought near 

 muriatic acid; but this minute portion of ammonia is pro- 

 bably only accidentally present. All the oxalates, which I 

 decomposed by distillation, were obtained by double decom- 

 position from oxalate of ammonia ; and though they were 

 washed with sufficient care, yet I thiiik it not unlikely, that 



a minute portion of oxalate of ammonia might continue to 

 adhere. Practical chemists know the extreme difficulty of 

 removing every trace of a salt, vv'ith which another has been 

 mixed. 



The carbonic acid remains partly combined with the base, Carbonic acid, 

 which always becomes a carbonate, and partly makes its es- 

 cape in the form of gas. 



The carbonic oxide and carbtiretted hidrogen make their Carbonic oxide 

 escape in the form of gas : the charcoal remains in the re- carburetted hi- 

 tort mixed with the base, to which it communicates a gray "^"S^'^'. ^^** 

 colour: the quantity of it depends in some measnre upon 

 the beat. If the oxalate wa? exposed to a very violf nt heat, 



tiO 



