Action of Chloride of Sulphur on Formiate of Baryta. 299 



The same chemist investigated* the action of chloride of sul- 

 phur on formiate of baryta and acetate and benzoate of soda. 

 By the first of these actions he hoped to get anhydrous formic 

 acid. But such is not the product of the action; there are 

 formed monohydrated formic acid and carbonic oxide : thus — 



4(BaO,C2H03)+3ClS=2S,BaOS0^3BaCl,4CO,2(C'^H03HO). 



Formiate of Monohydrated 



baryta. formic acid. 



The reaction gives a method for the preparation of monohydrated 

 formic acid, which consists in mixing four equivalents of an an- 

 hydrous formiate with four equivalents of water, and then adding 

 three equivalents of chloride of sulphur. By distilling the mix- 

 ture at a temperature of 100° C. to 120° C, pure monohydrated 

 formic acid is obtained. 



An acid formiate of soda or potash cannot be formed, and hence 

 themethodusedbyMelsens for producing monohydrated acetic acid 

 from binacetate of potash is inapplicable in the case of formic acid. 



Heintz found that chloride of sulphur acts on anhydrous organic 

 salts in such a manner, that a chloride and sulphate of the metal 

 are produced and sulphur separated ; and the sulphur separated 

 crystallizes from boiling alcohol partly in the form of rhombic 

 octahedra, and partly in that of long acicular crystals. The 

 same is the case with sulphur separated by acids from solution 

 of sulphide of sodium or potassium. 



Anhydrous acetate of soda gives with chloride pf sulphur 

 anhydrous acetic acid according to the equation— ^ „' |>^)iff^<;i oif^ 



4(NaO, C4 H^ 0^) +3C1 S = Na CI, NaO SO^ 2S, 4(0^ H^ O^). 



Acetate of soda. Anhydrous acetic 



acid. 

 But there are formed at the same time various collateral products, 

 especially sulphur compounds, and in certain cases a liquid 

 heavier and less volatile than water, and not miscible with it. 



In the endeavour to produce anhydrous acetic acid by heating 

 acetate of mercury, there were produced acetone, and a substance 

 containing more oxygen than it, but which was not formic acid. 



When chloride of sulphur acts on anhydrous benzoate of soda, 

 chloride of benzoyle is first formed, which reacting on an excess 

 of benzoate of soda, produces anhydrous benzoic acid and chlo- 

 ride of sodium : — 

 2(Ci4H50^NaO) + 3ClS = 2S + NaOSO^+NaCl + 2(C'4H^^j), 



Benzoate of soda. /.,.v ,*,.,.. vi,i,,. r^^ ^ • -, /. 



r t ' ' r ft Chloride oi . 

 ■mu ■ ih'yn^ojqei ^^(ho6 benzoyle. ; 



C14 H^ ^j + (NaO, C'4 H5 0^) = 2(0^^ ^5 qs) _,_ Na CL rni'^ 



„, , . , „ Benzoate of soda. Anhydrous ''■. , 



Chloride of benzoic acid, 



benzoyle. 5 



* Poggendorff*s Annalen, July. 



