334 
Wisconsin Academy of Sciences , Arts and Letters. 
Preparation: 
1. Analogous to that of the hydrobromide. 
2. From terpin hydrate: to 5 g. terpin hydrate contained in a flask 
about 20 cbcm. of cone, hydriodic acid (spec. grav. 1.96) are added and the 
mixture is shaken without the application of heat. The transformation 
into the iodide takes place quantitavely. The drained product is crys¬ 
tallized from petroleumether in which terpin hydrate is almost insol¬ 
uble. 51 
THE HYDRATES OF THE LIMONENE GROUP. 
Terpin and Terpin-hydrate. 
Synonyms. 
Pyrocamphorium 1 — Trautwein. 
Terpenthin salz 1 — Buchner, 2 1820. 
Terpentinolcamphorid 1 — Trommsdorf, 3 1828. 
Terpin 1 — Berzelius, 4 List, 5 & 9 1848. 
Trihydrate d’essence de terebenthine 1 — Deville. 
Turpentine camphor 1 (C 20 C 20 Q 4 ). 
Hydrate of oil of turpentine. 1 
* Terpenthincampher — Blanchet and Sell, 6 1833. 
*Wachholderbeerenolhydrat ( Bi anc 
* Terpenthinhydrat \ 
Terpenthincampher — Wiggers, 8 1840. 
Terpentinolhydrat, 9 1884. 
Hydrate de terebenthine 
Bihydrate d’essence de terebenthine 
Terpinhydrat — Wallach. 11 
History. 
Disregarding the dehydration products the chemical literature of ter¬ 
pin, resp. of terpin hydrate at first sight appears to be very simple. Ac- • 
cording to Gmelin 1 terpin hydrate was observed as early as 1827, by 
Geoffroy; Buchner 2 is stated to have regarded it as a salt of succinic 
acid with a volatile base, whereas Dumas and Peligot 12 and then Wiggers 8 
considered it to be a hydrate of turpentine oil. It is rather strange that 
Blanchet and Sell 7 are not mentioned by Gmelin in his historical re¬ 
view. The same views, however, have been expressed before, viz.: 
by Blanchet and Sell, 13 by the publishers of the “Annalen der 
Chemie und Pharmacie,” and by List. They are the same we find in our 
* Those marked with *, no doubt, pertain not to terpin or its hydrate but to pinol hydrate 
which was not recognized as such at the time. 
