VOL. LXX.J PHILOSOPHICAL TRANSACTIONS. 6; I 



of a brown colour; these were subjected to fusion, as in exper. 47, and after- 

 wards dissolved in distilled water. This solution being evaporated, it yielded trans- 

 parent hexagonal crystals, terminated by a plane surface. This salt has a sharp 

 taste, but is not so pungent as sal ammoniac; it dissolves readily in water, but 

 does not deliquesce in the air; it is not soluble in sp. of wine. Dr. C. thinks it 

 might be called sal calcarium animale. 



Exper. 50. This acid dissolves magnesia alba with effervescence. Two dr. of 

 the acid are sufficient for saturating Q dr. of this earth. The compound is not 

 crystallizable. 



Exper. 5 1 . The earth of alum, though not without difficulty, combined with 

 this acid. Two dr. of the acid were added to -i- dr.* of the precipitate, in a moist 

 state, obtained from alum by means of a fixed alkaline salt. At first the whole 

 appeared to be dissolved; but in a short time a considerable part, seemingly about 

 half, settled at the bottom. The filtrated liquor could not be brought to crys- 

 tallize; it had an astringent, not sweetish, but rather austere taste. On adding 

 an alkali, the dissolved earth was immediately precipitated. It may be called 

 alumen animale. 



Exper. 52. Siliceous earth did not appear to be acted on by this acid. 



Exper. 53. To obtain this acid in a concentrated state, which was a primary 

 object in these experiments. Dr. C. added to 12 dr. of the salt compounded of 

 the aforesaid acid and the vegetable alkali, 4 oz. of oil of vitriol, and afterwards 

 distilled off the (sebacic) acid in a gentle heat. It came over in the form of 

 grey vapours. The distilled liquor was as limpid as water, was strongly acid, and 

 weighed \ oz. 



Exper. 54. Half an oz. of the concentrated acid, exp. 53, was mixed with 

 an equal quantity of sp. of wine, and then digested and distilled. The liquor 

 which passed over into the receiver had the same smell as the ol. vini. On adding 

 water to it, the liquor turned milky ; but it soon after became clear, the oil rising 

 up to the surface. It had an aromatic taste, but in a less degree than theol. vini. 



Exber. 55. A solution of the oil in sp. of wine being subjected to distillation, 

 some ether (naphtha) passed over into the receiver. In this operation, the acid 

 uniting more intimately with the sp. of wine, and'both being more volatile than 

 the oil, they were separated from it. 



XII. A Conjecture concerning the Method bj which Cardans Rules for resolving 

 the Cubic Equation x^ -\- qx = r in all cases (or in all magnitudes of the 

 known quantities q and r) and the Cubic Equation x^ — qx = r in the first 

 Case of it (or when r is greater than ^^'^^, or '-^ is greater than —) were pro- 



* It does not seem to act on the exsiccated aluminous earth : and J dr. after all the humidity was 

 expelled from it, weighed only 4 gr. 



