Miscellanies. 195 
ed by the discoverers the Aydrure of guiacile; it is perfectly colorless 
when pure, and unalterable in the air, but in contact with potash and the 
air it acquires all the changes that a solution of the resin does. 
Parietin, by Roserr D. Tuomson, (Lon. and Ed. Phil. Mag. July, 
1844, p, 39.)—This is a yellow coloring substance obtained from some 
of the lichens. It was procured by digesting the yellow parmelia in cold 
alcohol of specific gravity ‘840, filtering, and allowing the alcohol to 
evaporate, when the coloring matter will be deposited in the form of fine 
yellow needle-shaped crystals. Composition and formula— 
20 
; pinesalg 65°85 
Bite Re Oey og a oe ae 
Ofte 4 ne higt eee Ypuiehe hep fio ie ggg 
100°00 
Parietin has been proposed as a test for alkalies,—its alcoholic solution 
becoming of a rich red by the addition of an alkali. \T'est-papers may 
be prepared by coloring paper with the solution. It is said to be better 
than turmeric for this purpose. The author thinks that it may be an 
oxide of an oil of the turpentine type, and mentions the following as be- 
ing a probable series— 
Oil of parietin, panied: tet gt A Ee 
Parietic acid, . : * ? ; €+°H1'§ O14 
Parietin, . , i ; ; ‘ Gt 15.014 
Oxide of parietin, . - O**, H26 O15 
Nitrogen Gas. (Chem. Gazette, July, 1844, p. 328.)—E. Marc#ANp 
has obtained this gas in a state of purity and with great ease, by heating 
in a retort a solution of chloride of lime and ammonia. 
Preparation of Carbonate of Potash free from Silica. ( Chem. Gaz. 
July, 1844, p. 328,)—One pound of crude of potash is dissolved in one _ 
pound of rain water, and four ounces of finely pulverized charcoal added 
to it. After standing for twenty four hours and being frequently stirred, 
it is filtered, when it will be found to contain no silica. 
Mixture of Pure Carbonates of Potash and Soda, by M. Du Merrit, 
(Chem. Gaz. Aug. 1844, p. 370.)—This mixture is frequently employed 
for decomposing silicates; it is prepared pure by red ucing Rochelle salts 
to an ash in a large crucible, and washing the mass with water. 
Ozone, by Prof. Scuénsein, (Bibl. Univ, de Genéve, Oct. 1844, p, 
420.)—For some account of this substance, see the Proceedings of the 
British Association published in this Journal, Vol. XLI, Pp. 43. M. Schon- 
bein has been continuing his researches upon this supposed new ele- 
* ment, and is more and more confirmed in his original views with regard 
to it, a detailed account of which is given in Pogg. Ann. Vol. 50, p. 616, 
and it would. be as well to-refer this. The peculiar smell observed by 
