Intellige7ice and Miscellaneous Articles. 155 



lime, or by sulphate of urea and lactate of oarytes. The oxalate of 

 urea has been described by Berzelius ; it is composed of 37*44 

 oxalic acid + 62 '5 6 urea; it is prepared by direct combination ; by 

 solution in water and evaporating with care, the salt is obtained 

 either in a mass of interlaced prismatic needles, or in pearly laminae. 

 The natural and artificial lactate of urea crystallize in elongated 

 six-sided prisms, the summits of which are inclined. These 

 crystals are white, hygrometric, and very deliquescent ; their taste is 

 cooling and sharp ; they are very soluble in water and in alcohol 

 and ajtherized alcohol, but much less so in pure sether. When 

 moderately heated they first fuse, then volatilize without decom- 

 position and sublime. If the heat be too great the salt decomposes, 

 leaving a black coaly residue. 

 Lactate of urea is formed of 



Lactic acid 50" 39 



Urea 49-61—100 



Or Lactic acid (anhydrous) ... 1 equivalent 



Urea 1 ditto 



Water 1 ditto 



Journal de Pharm. Mars 1839. 



SUBSESQUIACETATE OF LEAD. BY F. WOHLER. 



Matteucci has accurately observed the manner in which acetate of 

 lead is affected at a high temperature, but he has not explained it, 

 for he was unacquainted with the true composition of acetic spirit. 

 ITie decomposition is in fact very simple, and affords another 

 instance of the ready explanation which might be given of the 

 decomposition of organic compounds at high temperatures, if it were 

 possible in every case to expose them to well-determined degrees of 

 heat uniformly throughout their mass. 



If anhydrous acetate of lead be exposed in a glass vessel to a 

 uniform temperature, it fuses, according to Matteucci, at 536°, into 

 a transparent liquid, which boils in a uniform manner at a little 

 higher temperature : the ebullition is due to the formation of car- 

 bonic acid and acetic spirit, which are given out ; and the latter 

 may be condensed by a long refrigerating tube. At last a period 

 arrives at which the salt suddenly loses its liquid state and 

 becomes a porous white mass ; thisis the subsesquiacetate of lead; it 

 dissolves readily in water, carbonate of lead separating, which is 

 formed as a secondary product in small quantity. The dense 

 solution, evaporated to the consistence of a syrup out of contact of 

 the air, deposits after some time the salt in pearly crystals ; they are 

 laminated and grouped in a concentric manner. 



This decomposition of the neutral acetate of lead consists then in 

 losing one third of its acetic acid at 536°, which is converted into 

 carbonic acid and acetic spirit, while the remaining two-thirds com- 

 bine with all the oxide to form a subsesquisalt, which is not decom- 

 posable at this temperature. — Journal de Pharm. Mars 1839. 



