363 



drous acid, and (reducing the formula to its simplest expression) one 

 atom of hydrogen less than the hydrated acid. Thus we have 

 C 14 H 10 O 3 anhydrous benzoic acid, C 14 H 10 O 4 peroxide of benzoyl, 

 and C 7 H 6 O 2 hydrated benzoic acid, C 7 H g O 2 peroxide of benzoyl, 

 as we have H 2 O water, and H 2 O 2 or HO for the peroxide of hydro- 

 gen. This body crystallizes from ether in large and brilliant crystals. 

 Heated a little above the boiling-point of water, it decomposes, with 

 a slight explosion and the evolution of carbonic acid. Boiled with 

 a solution of potash, it is resolved into oxygen gas and benzoic acid. 



The peroxide of acetyl is prepared by mixing anhydrous acetic 

 acid and peroxide of barium, in equivalent proportions, in anhydrous 

 ether. The mixture is to be effected very gradually, being attended 

 with evolution of heat. The ether, after filtration from the acetate 

 of baryta produced, is to be carefully distilled off at a low tempera- 

 ture, and the fluid which remains washed with water. After three 

 or four washings, the water ceases to be acid, and a viscid liquid re- 

 mains, which is the peroxide of acetyl. This substance possesses 

 the following properties : It is extremely pungent to the taste ; the 

 smallest portion of it placed upon the tongue burns like cayenne 

 pepper. The substance suspended in water immediately decolorizes 

 a solution of sulphate of indigo. It instantly peroxides the prot- 

 oxide of manganese, and converts the yellow prussiate of potash to 

 the condition of red prussiate. Baryta-water poured upon the sub- 

 stance is converted to the condition of peroxide of barium, with for- 

 mation of acetate of baryta. Lastly, a single drop of the substance 

 itself, placed on a watch-glass and heated, explodes with a loud re- 

 port, shivering the glass to atoms. 



To analyse the peroxide of acetyl, I availed myself of its decom- 

 position by baryta- water. An undetermined quantity of the sub- 

 stance was thus decomposed, and the oxygen estimated which was 

 evolved by the decomposition of the peroxide of barium formed, by 

 platina-black, and the acetate of baryta determined as sulphate. The 

 result is the same as though the peroxide of acetyl were decomposed 

 into anhydrous acetic acid and oxygen, thus, 



C 4 H C 4 =C 4 H 6 3 + 0. 



Thus for every 1 6 parts of oxygen evolved, 2 equivalents of acetate 



