1822.] Scientific Intelligence. 389 
of peppermint, and in a day or two is entirely deprived of it. The 
same effect is produced on other distilled waters, and on mixtures of 
other essential oils with water in the proportion of one drop to two 
ounce measures of water. When, however, olive oil is substituted for 
castor oil, a nice palate may distinguish a very slight flavour. - 
II. Analyses of Magnesite. By M. Berthier.* 
This substance, commonly denominated meerschaum, forms with 
water a viscous and slightly plastic paste, resembling that of starch; 
it is easily attacked by the strong acids, and it gelatinizes with them : 
it contains much water of combination, which it gives up entirely at a 
red heat, without changing its form, or losing its consistence. It con- 
sists essentially of silicate of magnesia ; but this is almost always mixed 
with some clay or silicate of alumina. 
The analyses were effected in the following manner: The quantity 
of water was estimated from the loss of weight by calcination ; a por- 
tion uncalcined was treated with nitric acid, mixéd with a little muriatic 
acid, the solution evaporated to dryness, and treated with acidulated 
water. ‘The residue was gelatinous silica, mixed, perhaps, with quartz 
and clay not acted upon by the acids. This, after being calcined, was 
boiled with liquid potash, which dissolved all the silica; and the undis- 
solved portion was examined by the usual means. The nitric solution 
was deprived of its alumina and iron by hydrosulphuret of potash, and 
ef its magnesia by potash; the amount of the latter being estimated 
‘* par difference.” 
Magnesite from 
Salinelle dep. Sia de 
Montmartre, 
Silica...... 0°500 .:.. 0°538 .... 0°540.... 0'510.... 0-510 
Magnesia... 0°250 .... 0938 .... 0240 .... 0°198.... 0-134 
ete .,5 O° 200; .... 2) O'200, o£ C200 one OC ): AO kee 
Alumma... — .... yg oe O014 ..66 0-044 2... 0170 
‘ ; Cabanas, near . 
Asia Minor, Madrid, Coulommiers. “"y,, Gant 
Oxide ofiron — >... 
ST ee eee es TOI gl eee 
—— 
1000 0-988 0°994 ‘1000 0-996 
It is evident, says M. Berthier, that these five varieties belong to 
the same species, and that this species is essentially composed of silica, 
magnesia, and water; but it is very difficult to obtain a certain know- 
ledge of the relative proportions of these principles, because there are 
no means of ascertaining the quantity of silica which is found in combi- 
nation with the alumina. 
He concludes, however, after some theoretical reasoning, that the 
following formula represents the composition of magnesite, 6 M 83 
Aq? + M Aq?.—(Annales des Mines, vii. 313.) 
Seems i 
Ill. Analyses of Native Carbonate of Magnesia. By the Same. 
Carbonate of magnesia is found, either in combination or in mixture, 
* The subjects of this notice, in conjunction with those of the following one, consti- 
tate the fourth section of a paper by M. Brongniart on the magnesite of the basin’ of 
Paris, &c,: an abstract of the preceding sections will appear m our next. 
