4L4 Miscellaneous Intelligence. 



composed by the heat of a spirit of wine lamp. — Annalen der 

 Physik, 1828. 



16. Gay Lussac on the Action ofPotassa on Organic Matters. — 

 M. Vauquelin, by treating pectic acid with potash in a crucible, 

 converted it into oxalate of potassa. This experiment suggested 

 to me the idea of submitting ligneous matter, which has an analogy 

 to pectic acid, to the same treatment, and I obtained the result I 

 expected. 



5 grains of cotton were put with 25 grains of pure potash and a 

 little water, into a platina crucible, and heated over a spirit lamp 

 much beneath redness. The cotton resisted the action of the alkali 

 at first, but ultimately softened, the mixture melted without under- 

 going carbonization, and hydrogen was disengaged. During the 

 tumefaction the mixture should be continually stirred. When it 

 had settled down, the mass was dissolved in water, and rendered 

 slightly acid by nitric acid. It then gave an abundant precipitate 

 with nitrate of lead, and this, operated upon by sulphuretted hydro- 

 gen, produced very fine crystals of oxalic acid. With nitrate of 

 lime, a voluminous precipitate of oxalate of lime was obtained. 



Wood sawdust, with the same treatment, gave the same result. 



Sugar, with 4 or 5 times its weight of potash, became, when 

 heated, at first brown, then white, and gave much oxalic acid. 



Starch formed a very glutinous mass with potash, which long 

 retained this state. More alkali occasioned liquefaction, the mix- 

 ture swelled, and oxalate of potash was produced. 



Gum and sugar of milk were also converted into oxalic acid with 

 the disengagement of hydrogen. 



The most remarkable transformation is'that of tartaric acid into 

 oxalic acid. There is no swelling, no blackening, and (which 

 merits particular attention) so little evolution of hydrogen, that it 

 may be considered as due to extraneous vegetable matter. When 

 the hydrogen is to be collected, the experiment may be made in a 

 retort to which a tube of glass has been attached, which is to be 

 plunged beneath a layer of water into mercury to prevent absorp- 

 tion. The retort being heated by a bath of mercury or oil, it will be 

 readily observed that a temperature of 400° F. at most is suffi- 

 cient to form the oxalic acid. 



Citric and mucic acid produced also much oxalic acid. I have 

 also obtained it from succinic acid, but the benzoic acid resisted the 

 action of the potassa, and remained unaltered. 



Acetate of potash heated with excess of potash became converted 

 into carbonate. A little oxalic acid was obtained, but it is very pro- 

 bable that it was due to extraneous vegetable matter. 



Colza oil, notwithstanding a great excess of potash, could not be 

 brought into fusion, and but very little oxalic acid was obtained. 



Amongst animal substances, silk, treated with potash, gave oxalic 

 acid with disengagement of hydrogen. Uric acid evolved ammonia. 



