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Chemistry and Physics. 63 
ance of carbon contacts by pressure, in the construction of an 
ic ur be m 
ured, and has applied it to the construction of a thermometer, 
barometer, and hygrometer of ‘extraordioaty delicacy, and to the 
“are of a rheostat of great simplicity. os 
On the Boiling Point of Sulphuric acid of various pret 
ot hoagh the boiling point of the most concentrated sulphuric 
acid—containi ining 98°5 per cent H,SO,—was carefully fixed by 
Marignac at 338°, no determination of the boiling ett pe of acid 
of less concentration has been made since Dalton E h 
undertaken to redetermine accurately these boiling ‘points ra the 
following method: About 150 ¢.c. of the acid to be examined 
was placed in a flask having a long and wide neck and heated to 
boiling. In the nia ne beer was so suspended by wires 
of platinum as to ntain entral position, the bulb bein 
wholly immersed in the Sean. ig by loss of water the strengt 
of the acid is increased, the boiling point must be determined at 
nning of ebullition. This the author takes to be the 
instant at which the stem of the thermometer is surrounded by 
transparent vapors, and a partial condensation takes place on the 
neck, the Sermenndics heenmn at the same time stationary for 
O, as abscissas, a curve is obtained which 
is very ne arly a parabola and by which the boiling scales may be 
obtained for reeneainte strengths.— Ber. Beri. Chem. Ges., Xi, 
m0, yee /B 
wholly replaced by ee giving rise to three series of bodies, 
C,H,,,,CSOH, C. 2: Bin COSH, sed ,CSSH, the first two 
which are isomers. The confusion in naming these bodies 
n 
gen nee upon pot cyanide, a materials being placed 
verted co heated on the water 
bath fort five or six days. The. ait said two layers of liquid, 
the upper one of which was a eR of sodium sulphydrate. 
