306 EFFLORESCENCE, &C, OF GLASS TUBES. 



Damp air did 2. "The adlio^ remained invariable as long as the air conti- 

 not anfwer fo j^^^j ^^ j^^^ damp air appeared lefs favourable to the pile. 

 well as dry, ap- -^ ' . r rr • • i_ 



parently. 3. The lame degree of electricity was communicated by the 



The clearklty pjig t„ ^ Leyden phial. 



was transrerrable rr^i i . , . ,. 



to the Leyden * he plates were only three inches m diameter. As they 



phial. had already been ufed for a pile in which wet fubftances were 



of the elearicky '^^^^'"P^^'^^' ^"^ were much corroded, I took off the oxided 



perhaps owing portions by a file ; but the plates ftill remained rough and un- 



of thVplatesT *^^^" 5 ^"^ ^" ^^'^ circumdance I afcribe my not obtaining a 



higher degree of eledricity. I have yet had no opportunity 



of repeating the experiment on a larger fcale ; but the refult I 



obtained appeared to me fufficient to render the aflfertfion of 



No reafon why Ritter at leafl queftionablc. I fee no reafon why glafs, thin 



nI>faa'?n?hT''^^''^*^*^^ fealing wax, or the like, ftiould not have the fame 



pile, as in the effefl on Volta's pile as in the condenfer. For the experiment 



condenfer. ^q fucceed, it is neceflary that the bits of elafs fliould be as thin 



The glafs muft , „, , r •>• t n .- i ,- , -■ 



be as thin and and even as pollible ; tor, it the itratum or air be too thick, it 

 even as poffiblc , Js natural that the elegit icity, wiiich is excited in fuch a feeble 

 of air may be fo. ^^S""^^ by. the dontad of the two metals, fliouId remain in- 

 active on the adjacent metallic pairs. 



XIX. 



ExlraSi from a Letter from i/r. J. B. Van den Sandl:, 

 Profejfor at Luxejnbourg, on the Efflorefcence and Decompo-. 

 fition of Glafa Tubes *. 



Oxidation of 1 HAVE lately had an opportunity of obferving atleifure the 

 uncommon."" common phenomenon of the calcination of white glafs. I ex- 

 Old baronaeter- pofed to the flame of an enameller's lamp fome old barometer 

 fllme *^tur^ned ^^ ^"^^^ *''^^ appeared not to have any defed, in order to bend 

 white and opakej them into (yphons. Scarcely had they come into contact with 

 the fiame, when they turned white and opake. One of the 

 tubes being wetted, I placed it on a chamber-ftove to dry ; and 

 before it was heated, it was covered with a whitifli effloref- 

 and the fame if ccnce. Heating the others produced on them the fame effect. 

 *mply heated. \ tijen removed the eflflorelcence, replaced the tubes on the 

 ilove, and they became white afrefh. By continuing the ex- 



* Journal de Chimie, par Van Mous, IV. p. 232. 



periments, 



