Sdentijic Intelligence, 181 



alic acid, which preserves greater fixity in uniting with that alkali : 

 we have not however yet succeeded in isolating this gelatinous mat- 

 ter, and in forming pectic acid by combining it with oxalic. 



The views w^hich I have often developed in my course, with res- 

 pect to the formation of acids in vegetables, are, that they are caused 

 principally by the presence of alkalies. We find, in fact, that acids 

 are almost always neutralized, in whole or in part, by various alkalies, 

 such as lime, potash, soda, magnesia, and sometimes also by vegeta- 

 ble alkalies ; and I do not know that these last have yet been found 

 uncombined in the vegetable kingdom. 



Among these alkalies, lime has certainly the greatest effect in the 

 vegetable kingdom, because it is more generally diffused over the 

 surface and attracts powerfully the acids. It does not, it is true, in 

 the condition of lime, enter organic substances, but rather in the state 

 of carbonate, which without exerting any deleterious action on veget- 

 ables, preserves sufficient alkaline force to determine the formation 

 of acids, and particularly the oxalic acid, which it prefers to all others. 



In this manner we may explain the effect of calcareous marls. 

 Immediately on its introduction into the organs of plants, the carbon- 

 ate of lime determines the developement of an acid which decomposes 

 it and sets free its carbonic acid, which, aided by light, turns to the 

 profit of the vegetable nature. Hence, it may be concluded, that 

 calcareous marls perform at once two important functions, viz. the 

 division of the soil, and the nutrition of plants. — Ann. de Chim. 

 Mai, 1829. 



22. Detection of corrosive sublimate. — J\I. Orjila discovers that 

 the test proposed by James Smittson, of dipping a strip of gold, sur- 

 mounted by a spiral of tin foil, into the suspected liquid, and adding 

 one or two drops of muriatic acid, does not afford a certain indica- 

 tion of the presence of mercury. The gold becomes whitened 

 without it, by the action of the muriatic acid on the tin j this effect 

 ensues, even in a solution of common salt, made by adding twelve 

 drops of a saturated solution of muriate of soda to one and a half 

 ounce of distilled water. When, however, the strip of gold becomes 

 whitened in the experiment, it may be ascertained by strong muriatic 

 acid, whether the effect has been produced by mercury or by tin. 

 If the latter, the tin dissolves entirely and the gold resumes its primi'- 

 tive color, but if the gold be whitened by mercury, it resists the ac- 

 tion of the acid, and remains of a greyish white. The muriatic acid 



