24 Historical Sketch of Improvements in [July, 



est part sublimes in long needles, but a portion is decomposed, 

 as happens to most vegetable bodies. 



Strong alcohol dissolves this acid very abundantly. Water, 

 at the temperature of 50^^, dissolves half its weight of it. The 

 solution reddens vegetable blues, precipitates acetate of lead 

 and nitrate of mercury in white flocks. It does not precipitate 

 lime-water. It precipitates barytes water in a white powder, 

 which is redissolved by the addition of water, and silvery plates 

 gradually attach themselves to the sides of the vessel, which are 

 pyromalate of barytes. This salt is a compound of 



Acid 100-000 5-266 



Barytes 185-142 9-750 



It would appear from this that the equivalent number for 

 pyroraalic acid is 5-25. 



Pyromalate of potash crystallizes in feather-shaped crystals. 

 It is somewhat deliquescent. Its solution in water does not 

 precipitate the salts of iron, copper, manganese, zinc, nickel, or 

 cobalt ; but when dropped into nitrates of silver, mercury, or 

 lead, a white flocky precipitate falls. 



The combination of this acid with oxide of lead presents some 

 remarkable phenomena. It is obtained at first in the state o 

 white fl.ocks, which, in a little time, assume the form of a semi 

 transparent jelly. When this jelly is diluted with water and 

 separated by the filter, it collapses in proportion as the water 

 leaves it, and after some time is completely crystallized in very 

 brilliant pearly needles. 



M. Lassaigne likewise examined the white crystals which 

 subhme when sorbic acid is heated. He finds them to possess 

 peculiar properties, and. therefore, considers them as entitled to 

 rank as a peculiar acid. (See Ann. de Chira. et de Phys. xi. 93.) 



8. AJeniapcruiic Acid. — M. Boullay made a set of experiments 

 on the seeds of the menispermum cocculus in the year 1812, and 

 extracted the ingredient to which these seeds owe their poison- 

 O.US qualities. This substance he distinguished by the name of 

 jncrotoxijie. He has lately shown that it possesses alkaline 

 properties, and that it exists in the seeds of the menispermum 

 cocculus united to an acid which he considers as possessed of 

 peculiar properties, and which he has distinguished by the name 

 of mcnispcnnic acid. 



This acid was extracted from the seeds by the following pro- 

 cess : The seeds were macerated in five times their weight of 

 water for 24 hours. They v.-ere then boiled for some time in a 

 quantity of fresh water. Into the liquids thus obtained, subtrit- 

 acetate of lead was dropped as long as any precipitate fell. The 

 grey-coloured precipitate thus formed was mixed with water, and 

 a current of sulphuretted hydrogen gas passed through it to 

 .^:;fiparate the lead. The liquid was now heated to drive off' the 

 excess of sulphuretted hydrogen. Its taste was acid, though 



