Page:Proceedings of the Royal Society of London Vol 4.djvu/267

Rh well as the mudesous acid itself, are oxidized and converted into a new brownish-yellow, soluble and deliquescent acid, containing more oxygen, and in the anhydrous state represented by H5 Oiq.

6. That this new acid, the mudesic, combines readily with alu- mina and protoxide of mercury, giving salts of a yellow colour. Both the acids described in this paper are distinguished for their tendency to precipitate alumina and the protoxide of mercury. The mudesate of mercury dried at 300° F., is represented by (2 Hg O + C12H5O10).

7. That chlorine, when made to act on either of the acids, or their salts of alumina in contact with water, gradually deprives them of all colour, while, at the same time, muriatic acid is formed. Col- lected on the filter, boiled in water till the washings cease to pre- cipitate nitrate of silver, and dried, the white gelatinous, apparently altered mudesite or mudesate, is found on analysis to contain no atomic proportion of chlorine, but to have sensibly the constitution of the mudesic acid, or mudesates prepared by the direct action of nitric acid. The author thinks it not unlikely that a chloro-mudesic acid exists, and may be formed during this process, represented probably by Cjg H^Cl Ojo, but which he has not succeeded in ob- taining in a separate state.

The mudesous and mudesic acids are distinguished from each other by giving, the former brown, and the latter yellow precipitates with the neutral metallic salts — by being the former unaltered, and the latter deliquescent in the air. Both form deliquescent salts with ammonia, and appear to undergo alteration by the long-continued action of hydrosulphuric, or of concentrated sulphuric and hydro- fluoric acids.

7. On the Constitution of the Resins, Part V. By James F. W. Johnston, Esq., M.A., F.R.S.

In this paper the author continues his examination of what are called the fetid resins, and from repeated analyses deduces for the resin of Sagapenum the formula C^q Ho,, O9, and for that of Galbanum C40 O7. He then compares the formulae for the four resins : Opoponax = C40 H25 O14, Assafcetida = C40 Hqs O^q, Galbanum = C40 H07 O^o, Sagapenum = C40 Hg^Og ; and considers it probable that, though no striking analogy among the irrational formulae for these resins is perceptible, by which their analogy in physical properties can be accounted for, that they may possess an analogous rational constitution, which future researches may disclose.

Euphorbium consists of two resins, of which the more soluble, A, gave the formula C40H3, Og. Elemi also consists of two resins, of which the more soluble. A, is represented by C40 H32 O4, and the less soluble, B, by C40 0„ as had previously been shown by Hess and Rose. The Bdellium of commerce contains much gum, and a resin C40H31 Oj,.

The resin of Benzoin presented peculiar difficulties when submitted to investigation, from the ease with which it undergoes de-