t 48 ] 



XT. Dr. Lam BE on Arsenic^ 



To Mr. Tilloch. 



Sir, J. HE experiments of which I herewith transmit you 

 an accoimt, form a part of a supplement to my experi- 

 ments on arsenic, read before the Royal Society this spring. 

 I wished them to be read before the san)e body tfiis season: 

 but having been disappointed in that expectation, and hav- 

 ing mentioned the principal fact to several persons, I wish 

 the following short account to be inserted in The Philoso- 

 phical Magazine. 



1 am, sir, ccc. 



2. King's Road, Bedford Row, WiLLIAM LaMBE. 



July 17, 1812. 



On the Decomposition of White Oxide of Arsenic hj Lime. 

 By William Lambe, M.D. 



I prepared some lime by exposing pieces of marble in a 

 crucible to the heat of a smith's forge, making it so 

 caustic, that no eflervescence took place by the affusion of 

 diluted muriatic acid, though a few minute bubbles were 

 still formed. To effect this, I found it necessary to keep 

 the ntariile in this strong heat two complete hours. I 

 mixed three ounces of this lime with its weight of white 

 oxide of arsenic, which I had previously sublimed and pul- 

 verized. The mixture was introduced into a coated glass 

 retort, to which a tube was joined, the end of which was 

 plunged into water in a pneumatic trough ; and the retort 

 was gradually made red hot. The water at first rose into 

 the tube, showing an absorption of gas by the matter in the 

 retort; but whcnlhc retort became red-hot, its neck became 

 covered, internallv, with moisture, and a cubic inch or two 

 of o-as was expelled, which was not soluble in any notable 

 proportion in water. After this, the water rose again into 

 the tube, and undulated for some time, up and down, with 

 a strong vibratory motion. Finally, three or four cubic 

 inches of gas were expelled, by far the greater part of which 

 proved to be carbonic acid. 



On breakino- ihe retort (which was done as soon as it 

 was cool) the lime was found to be converted into car- 

 bonate of lime ; being completely neutralized, and efTer- 

 vcscing strongly with an acid. 



It is readity demonstrable, that the carbonic acid and 

 water produced in this experiment are formed at the ex- 

 pense of the arsenic. Some of the oxide is retained by the 



lime. 



