44 REPORT — 1875. 



yield by atmospheric oxidation acetic acid and 2^^>'oxide of hydrogen, and probably 

 other bodies as yet undetermined. 



Thus Hesperidenc (the terpene of oil of orange-peel) yielded an acid solution 

 containing in 100 cub. ceutims. OlSi gi-amme peroxide of hydi-ogen ; and, moreover, 

 a copper salt was prepared from an* Jicid (not acetic) existing in solution which 

 contained 12-85 per cent, copper. This acid is not precipitated from its combination 

 with soda by acetic acid. 



Myristicene. — With this terpene three experiments were made. 



«, With ordinary oil of nutmeg. This yielded, when oxidized in the presence 

 of water, an acid solution containing in one case 0"098 gramme peroxide of hydrogen 

 in 100 cub. centims. 



h. This experiment was made with the terpene isolated from nutmeg-oil by sodium 

 treatment and fractional distillation. It boiled at 164° C, and consisted of terpene 

 containing a little cymene. It yielded by oxidation a solution containing 0'0915 

 gramme peroxide of hydrogen in 100 cub. ceutims. 



c. This third trial was made with that fraction of nutmeg-oil, hydrocarbons, 

 boiling at 173°-ir6°, and therefore mainly cymene (as shown by Wright). This 

 gave, on oxidation with water, a solution containing 0'0114 gi-amme H20j, in 100 

 cub. centims. 



Wormioood. — Wright (Journ. Chem. Soc. vol. xii. p. 317) has shown this oil to 

 consist mainly of an oxidized body, Cj^ H,g O, containing some terpene. 



It yielded peroxide of hj'drogeu on oxidation, although in small quantity. 



Citronella contains, as Wright has shown, no terpene, but is mainly an oxidized 

 body, C,„ H,3 O. It yielded, as was to be expected, no li^ O.^ on oxidation. 



Yhlang- Ylilang. — This perfume (see a paper by H. Gil in 'Year-book of Pharmacy,' 

 1874) contains no terpene. It was subjected to atmospheric exposiuo in sunshine 

 as a test, but developed no peroxide of hydrogen, showing it to contain no terpene, 

 a result found by other means by H. Gil. 



The oils of caraway, bergamotte, juniper, cubebs, lemon, and chamomile also 

 absorb oxygen from air, forming in the presence of water peroxide of hydrogen. 

 Their essential terpenes in a pm-e state have not yet been examined. 



Such bodies of the formula Cj, H^^ as I have examined fail to develop H^ 0^ by 

 atmospheric oxidation. 



This is true at least of the so-called clove terpene, isolated by Church from oil of 

 cloves (Jom-n. of Chem. Soc. ser. 2, vol. xiii. p. 113), and also of patchouli, although 

 it is to be remarked that the patchouli I examined was not oxidized by myself; 

 and so the experiment requires repetition. 



Cymene from all sources is identical, as proved by the researches of Fittica, 

 AVright, and Paterno, «fcc. I have oxidized three samples : — 



a. Cymene from camphor by zinc chloride. Of this 7 cub. centims. absorbed 

 52 cub. ceutims. oxygen in 18 days, and formed peroxide of hydrogen. 



h. Cymene from the dibromide of cajeputol, boiling at 176°-177°, gave by oxida- 

 tion with water a solution containing 0-196 gramme H^ O^ in 100 cub. centims. 



c. A mixture of quantities of cymene from various sources. This also gave 

 affirmative results. Besides peroxide of hydrogen so obtained by atmospheric 

 oxidation of cymene, a toluic acid seems also to be formed. A. crystallized acid 

 was obtained from the solution- having the ordinary characters of a toluic acid; 

 but there was not sufficient quantity to admit of analj-sis. 



It is to be remarked that the oxidation in eacli case was effected by exposing the 

 oils with water to sunshine and air, or passing a ciu-rent of air through the mixture 

 at40°C. 



I have shown, in Parts I. and 11. of this research, that turpentine by oxidation in 

 this way gives rise to the formation of campho-ic acid and peroxide of hydrogen 

 indirectly — that is, by the decomposition by water of a previously formed peroxide 

 of an organic nature. 



Bodies of C^j, Hg, composition have not yet been examined. 



These researches also prove that cymene is the nucleus matter of the terpenes ; 

 and thus is established another link between the terpenes and the benzene series. 



Fittica (Deut.Chem. Ges. Ber. vii. 323) has shown cymene to be normal propyl- 

 methyl-benzene in which the methyl and propyl occupy the paraposition. 



