Chemistry and Physics. 55 
this case, the liquid is —_— to ~ an hour, filtered off, and a 
nia added to the filtrate. A precipitate dinates 
the reais of ni ara in amount . least two per cent. e 
presence of calcium and sodium salts in the quinidine sulphate is 
readily detected by solution in coils when these are left be- 
quinine or cinchonidine are also present, one gram of the 
substance is to be treated with seven cubic centimeters of a mix- 
_ture of two volumes chloroform and one volume 97 a cent 
et —Liebigs Annalen, clxxvi, 322, May, aa G. 
Mechanical Equivalent of Heat.— M. H. J. Puwvs had de- 
sore an apparatus of very simple Spvauniyai for as this 
constant, suitable for use in the lecture-room, It consists of a 
put 
in motion and the inner cone fixed, heat is generated by the friction 
of the surfaces, 
n arrangement which is an inversion of Prony’s check serves 
for the measurement of the work which is converted into heat. On 
the wooden lid of the inner cone a light wooden beam is screwed 
horizontally. A perforation rere through the beam and lid re- 
ceives the thermometer, At some distance from the beam is a fixed 
pulley, on a level with it, over which a thread, to which a scale is 
suspended, is slung and is fastened to the end of one arm of the 
eam ; the other arm serves as a counterpoise. When the machine 
is set in motion, the interior face of the outer cone rubs against the 
surface of the inner one and tends to turn the beam, which is fas- 
tened to the latter, in the direction of the motion. With a certain 
mechanica al bqatonlant of heat from 28 experiments. The mean of 
the results, the 425-2, with the mean error +-5°4, is in qocllent 
accordance with Joule’s result, 424°9, and may be regarded not 
periment proper lasti ng bu t 30-60 seconds, on which account the 
apparatus may be ae oe for lectare-experimenta— Loy. 
Acad. Vien., April, 1875; Phil. Mag., xlix, 416 
