586 BEPORT — 1881. 



bined, the calculated number in that case being 73'82. Menthene combines with 

 fuming hydric chloride, forming a slightly yellow oil, C'HjgGl. 



Hydrocarbon. — C'^Hi,,. This is the principal product found by cohobating 

 menthol with a strong solution of hydric iodide, boiling with caustic soda, and 

 finally digesting with sodium. It boils at 168'6° (corr.), but analysis showed 

 that it still retained traces of menthene, which appears to be found in the same 

 reaction. The specific gravities and volumes at different temperatures are given 

 in the original paper, the specific gravity at 0° being 0-8263. The specific rotatory 

 power was 6'2° for the transition tint. The molecular refraction was 73'28, the 

 calculated value for four atoms of carbon doubly combined, being 73'24. 



Remarks are made upon the difficulties met with in determining the specific 

 volumes of the above compounds, and the paper concludes with a discussion of the 

 probable constitution of menthol and its derivatives, in which the resemblance 

 between camphor and mentbone is pointed out. 



8. On the Sodlwn-alum of Japan. By Professor Edward Divers, M.D. 



The mineral sodium alum, since called Mendozite, was described by Thomson 

 in 1828, as occurring in South America (St. Juan, near Mendoza). Its occurrence 

 has not been noticed elsewhere. 



Eammelsberg ('Mineral. Ohemie') gives a series of percentages as obtained by 

 Thomson, and refers them to an alum vrith twenty molecules of water. Dana 

 (' System of Mineralogy ') gives a different series as obtained by Thomson, and 

 refers them to an alum with twenty-two molecules of water. 



My late assistant, Mr. J. Mori, once a pupil of the Royal College of Chemistry, 

 South Kensington, analysed the specimen I have now to describe, and obtained the 

 following results : — 



Calculated for 

 Found AI0O5, NaoO, 4SO3, 24H2O 



Alumina . . . 11-27 . . . 11 -23 

 Soda .... 7-26 . . . 6'76 



Sulphuric Oxide . . 34-73 . . . 34-90 

 Water .... 4674 (by difE.) . 47-11 



- 100-00 10000 



The soda is too high, else the results are most satisfactory, but error in excess 

 here is probable from imperfect ignition to expel ammonium sulphate. Thomson 

 found 7-96 soda, whereas for 22 Aq. alum only 7-1 are required. Potash is absent 

 and only traces of iron, calcium, and insoluble matter are present. 



Sodium-alum, therefore, occurs in nature of the normal type, with twenty- 

 four molecules of water. 



It occm-s as an efflorescence on decomposing sodium (albite) felsite, with pyrites 

 scattered through it. It is found in the province of Idzumo, in the prefecture of 

 Shiman^, Japan, not far from the coast. Like that examined by Thomson, it is 

 not produced by a solfatara, though Shiman^, like many parts of Japan, includes 

 such. The alum is said to be obtainable in considerable quantity ; but as a second 

 parcel forwarded to me was damaged in transit by the leakage of bottles of natural 

 alum-water I have only been able to examine very small specimens as yet. 



It occurs in two forms — one massive, finely fibrous, greyish white, translucent ; 

 and also in friable opaque tears, slightly coloured by iron hydrate or oxide. 



9. On tlte Occurrence of Selenium and Telhirium, in Japan. 

 By Professor Edward Divers, M.I). 



At the sulphuric acid works of the Imperial Japanese Mint, and at a private 

 ■establishment, both in Osaka, the sulphur now employed comes from different parts 

 of Japan — Kagoshima, Oita, Hokkaido, &c. In some of the sulphiu-ic acid made 

 there, I have found not inconsiderable quantities of selenium, and Mr. M. Shimos^, 



