Van-Marum’s Gazometer, 8c. 83 
Dr. Beddoes, fubjoins the. following P. $.—“ A lady to 
whom I recommended the ufe of charcoal-powder as a den- 
tifrice, was fubjeét at times. to violent tooth-achce, from one 
of the dentes fapientiz that was become carious. She one 
day, when in great pain, filled the cavity of the tooth with 
the charcoal dentifrice, and was furprifed to find herfelfin a 
few feconds free from pain. It might probably be urged, 
that any fubftance filling the hollow of the tooth mechani- 
cally, and thereby preventing the accefs of atmofpheric air, 
would produce the fame effe&t: but I am rather inclined to 
attribute the éemporary good effect experienced in, this 
cafe, to the power,of the charcoal *. 
XVIII. Defcription of the Gazometer. invented by M. Van 
Marum and his Apparatus for producing Water, by, the 
Combujiion, of Hydrogen in\Oxygen Gaz. From the An- 
nales de.Chemie, Vol. XII. 
Tue yeffel 11 inches in diameter, containing the air or 
Zaz to be employed, is reprefented by A, The mouth of it - 
is clofed by a brafs cover {crewed upon it, and furnifhed with - 
three cocks B, C, D. On the cock B is ferewed)a copper 
fyphon EF, haying its end F ferewed upon another brafs 
tube open at the bottom, reprefented by the dotted lines 
GG, and which defcends within the brafs cylinder Hj which 
is open at,the top. To the lower, part of the cock B is ce- 
mented a glafs tube II, which is open at the lower end 
near the bottom of the glafs. _ When the cock B isiopened, 
sthe tubes G G, F E, 1.1, make only one fyphon;, from 
which, when it is completely full, and. the water|in both 
yeflels does not ftand on the fame horizontal line, the svater 
* Any of our readers who try this fimple application, will ob! ige us by 
‘communicating the refult, to determine, whether charcoal be a remedy for 
the tooth-ache, or whether we muft attribute the above cafe’ toa natural 
ceffation of pain. 
G3 ~ will 
