36 REPORT— 1842. 



found that magnesian protoxides were very apt to form compounds with magnesian 

 peroxides of the general formula R O + R» 4 . Hydrogen itself possesses all the 

 characters of a magnesian metal, and hence should share this aptitude. Thenard 

 found a deficiency of oxygen in the compounds obtained by him. This deficiency 

 would be accounted for on Dr. Play fair's view, that they consisted of peroxide of 

 hydrogen with a metallic protoxide, of the formula MO + H, 4 , corresponding to 

 the compounds obtained by the author, R O + R 2 4 . On this view, the proportion 

 of the radical to the oxygen would be 3 : 5, whilst on Thenard's formula of R 2 , it 

 would be 3 : 6. 



Dr. Playfair then described at length the manner in which he prepared the true 

 peroxides ; chloride of soda was employed to effect their oxidation. He had obtained 

 a peroxide of copper of a brown colour, which evolved oxygen when dissolved in 

 acids, and chlorine with muriatic acid. In its highest state of hydration it contained 

 2 atoms of water ; at 212°, 1% atom is expelled, thus showing that the correct for- 

 mula of the oxide is Cu 2 4 . The water is held with different degrees of force, and 

 compounds were described in which this water is replaced by oxide of copper. The 

 author also obtained a compound of this peroxide with a sesquioxide of copper, 

 corresponding to the mineral varvacite (Mn O + Mn 2 4 ) +HO. The new body 

 possesses the analogous formula (Cu 2 3 + Cu 2 4 ) + H O. 



The author also obtained a peroxide of iron (Fe O s ) by similar treatment. It pos- 

 sesses analogous characters with peroxide of copper. Thus it contains 2 atoms of 

 water, half an atom of which is held with considerable force. This peroxide is sus- 

 ceptible of entering into combination with the sesquioxide of iron, and of forming a 

 compound corresponding to varvacite in chemical composition. The author had also 

 obtained a peroxide of aluminium of similar properties with the preceding peroxides, 

 but which differed in its relation to water. He concluded by announcing the dis- 

 covery of some new oxides of zinc and chromium, the examination of which were 

 not yet completed. 



Note on the Composition and Characters of Caryophyllin. 

 By Dr. Lyon Playfair. 



Caryophyllin may best be prepared by digesting cloves with alcohol for several 

 days, in the manner described in Liebig's 'Organic Chemistry.' When pure, it is a 

 snow-white crystalline substance, insoluble in water, but easily soluble- in hot 

 alcohol. The addition of caustic ammonia or caustic potash to the alcoholic solu- 

 tion does not occasion decomposition or precipitation. Caryophyllin has been ana- 

 lysed by Dumas and Ettling, who found it to possess the formula Cio H 16 2 . The 

 author of this paper found that, although this was the correct expression of the com- 

 position of melted caryophyllin, it was not so of that body in its natural state. He 

 found caryophyllin, kept for three days at 212°, to possess the empirical formula 

 C 40 H 33 5 , or the rational formula C 40 H 32 4 + H O. This shows that the formula 

 given by Dumas and Ettling must be quadrupled. The anhydrous caryophyllin 

 would seem to show that it is isomeric with common camphor, but this hydrate 

 proves that it possesses twice its atomic weight, and brings it into the same category 

 of bodies with pinic, silvic, and copahuvic acids. Caryophyllin has always been sup- 

 posed to be an indifferent body, but the author showed that it is a weak acid, capable 

 of forming salts. Caryophyllite of potash (from which all the metallic salts may be 

 procured by double decomposition) is obtained by dissolving caryophyllin in an alco- 

 holic solution of potash, agitating the mixture with an excess of bicarbonate of 

 potash, evaporating the whole to dryness, and dissolving out the caryophyllite of 

 potash with anhydrous alcohol. The salts formed with metallic oxides and caryo- 

 phyllin are insoluble. Caryophyllite of potash is a white saponaceous body with a 

 crystalline appearance. 



The oil of cloves possesses the formula C, H s . By the absorption of one atom of 

 oxygen it would be converted into caryophyllin, C 10 Hs O = C 40 . H 32 4 . The 

 simplest view would, therefore, be to suppose that caryophyllin is a product of the 

 oxidation of the indifferent oil of cloves, and not an educt of the cloves them- 

 selves. 



