On the Strata of England. 49 



lime, and some more (hut blackened) is sublimed into t!ie 

 neck of the retort; but, upon the whole, there is a consi- 

 derable loss of weight of the arsenic. But the more mi- 

 nute details of the experiment, with some other nhseno- 

 mena connected with it, I must reserve till I can brina; be- 

 fore the iniblic the memoir of whicli it forms a part. 



I must here observe, that for ihe success of this experi- 

 ment, it is essential that it be performed in close vessels. 

 It will not succeed in an open crucible. Three times I 

 have failed when using glass retorts. Some carbonic acid 

 was expelled from the tube as before, but mixed with a 

 large proportion of insoluble gas ; and little or no carbo- 

 nate of lime was found ; but a new compound, with the 

 nature of which I am not at present perfecily acquainted. 

 In each these experiments, it appeared that a hole had been 

 formed in the retort, and the difference of the result must 

 be attributed, therefore, to the admission of atmospheric 

 air. 



When I used common lime, which was verv caustic, I 

 found the production of carbonic acid, apparently, much 

 more abundant. From three ounces of this lime, and an 

 equal weight of white arsenic, I procured 90 cubic inches 

 of carbonic acid, and the lime was likewise converted into 

 carbonate of lime. 



Finally, I have once used lime which had been exposed 

 to so intense a heat that the crucible was partly melted. 

 This lime put into an acid did not emit the smallest bubble 

 of gas. Heated, in close vessels, with its weight of white 

 oxide of arsenic, some carbonic acid was produced : but 

 the niatter in the retort did not prove to be carbonate of 

 lime; but another compound with the nature of Vv^hich 

 I am at present no further acquainted, than that it dissolves 

 in muriatic acid without eff';rvesceiice, and forms a cry- 

 stallizable salt. 



XII. On certain Points comiccied iiilh the Supf-r-position of 

 the Strata of England. By David Mumiet, Esq. 



To Mr. niloc/i. 



Sib, J. HE subject of stratification has lately been so ably 

 treated in your valuable Magazine i)y Mr. .lohn Farey, that 

 it cannot fail to excite a very great interest among those 

 inlercsted in the success of geological and philt)so[)hical 

 pursuits. With a patriotism truly laudable, Mr. Farey in- 

 vites his countrymen to the study of the subject at home, 

 Vol. 40. No. n I. July I8l'2. D as 



