749 



substance of which the greater part of the cerin consists is no alde- 

 hyde, but a hydrated acid, existing- as such in bees'-wax. 



The acid is best prepared by precipitation from the alcoholic solu- 

 tion of the cerin by an alcoholic solution of acetate of lead, and sub- 

 sequent separation and precipitation of the acid by methods described 

 in the present paper. When purified, the acid is a white brittle 

 body, of a crystalline appearance, melting at from 79° to 80° C. 

 The formula of the acid is C^4 H34 O4, a formula which was deter- 

 mined by the analysis of the silver salt having the constitution C54 

 H53 O: + AgO, and of the compound ether C33 H^g O4 = C54 H;,3 

 0,3 + C4 O. The acid is volatile : it was analysed after distilla- 

 tion; and it was also procured from the wax itself in a pure state by- 

 simple processes of crystallization. To this acid the author gives 

 the name of Cerotic acid. 



By the action of chlorine, the wax acid is converted into a sub- 

 stance having all the appearance of a gum-resin ; a change analogous 

 to which may be effected in various other wax substances examined 

 by the author. It has still the characters of an acid, and has the 



r H 



formula C^4 <^ ^^^'^ O4, a formula which is confirmed by that of the 

 ^J'' O4. The analyses of these substances are 



given. 



When distilled in a pure state, the cerotic acid is volatile. When 

 mixed with other waxy matters, however, it passes by distillation 

 entirely into volatile oils, a circumstance which accounts for the fact 

 that it has never been dissolved in the wax distillate. By precipi- 

 tating a weighed quantity of wax by acetate of lead, the quantity 

 per cent, of the cerotic acid in the bees'-wax, namely 22, was deter- 

 mined. 



This acid was present in all the European bees'-wax examined by 

 the author ; but suspecting that its quantity might vary in other in- 

 stances, he procured bees'-wax from Ceylon, formed under different 

 conditions of climate and vegetation, and found on examination that 

 there was a total absence of the acid in that specimen. The author 

 draws attention to this curious variation in the nature of an animal 

 secretion under different conditions of life, a variation of which we 

 have another example in that of the volatile acid of butter, discovered, 

 by Leich ; namely, that the butyric and caproic acid of one season 

 v/ere, in another, replaced by vaccinic acid, differing from the former 

 acids in the amount of oxygen alone. 



" A statement of the working of the Compasses on board the 

 Honorable East India Company's Iron Steamer Pluto, from Septem- 

 ber 1841, on her passage from England to China, and during her 

 service in those seas, until her arrival at Calcutta in January 1843." 

 By John Tudor, Commander R.N. Communicated by S. Hunter 

 Christie, Esq., Sec. R.S., &c. 



The author states that the compasses of the Pluto were adjusted 

 by Mr. Sims, of the firm of Troughton and Sims, by order of Mr. 



