Chemistry and Physics. 408 
those which teach Chemistry as a science and aim to make 
chemists, and those which teach it as an art and aim to make 
analysts. Professor Bloxam’s book, to judge from the somewhat 
extraordinary preface to the fourth edition, belongs evidently to 
the latter class. He says: ‘The most important alteration in the 
present edition is the introduction of the formule representing the 
aa chemical compounds described in the notes to the tables. 
, do ‘ 
acid (H.NO,); but both these substances are obtainable from salt- 
peter by very simple chemical operations, and saltpeter may be 
produced by causing them to act upon each other. It is true that 
Similar reasoning would justify the statement that common salt 
contained soda and hydrochloric acid instead of sodium and chlo- 
rine, but the author feels that an endeavor to be absolutely con- 
' ysics. — On the occasion of the partial eclipse 
observed at Marseilles on the 19th of July, 1879, M. Janssen 
poses to take, by means of a revolver, a number of solar images of 
0"-06 to 0-10 in diameter, at intervals of one second, By opti- 
cal methods the contacts cannot be observed with precision, on 
Am. Jour. Sct.—Turep Serres, Vou. XVIII, No. 107.—Nov., 1879. 
26 
