[1] I.e., the time-curve.—ED.
[2] The author seems to refer to the fact that in the standard metre, the measurement is taken from the central one of three marks at each end of the bar. The transverse section of the bar is an X, and the reading is made by a microscope.—ED.
[3] I.e. 1/2000 of a millimetre.—ED.
[4] These are the magnitudes and units adopted at the International Congress of Electricians in 1904. For their definition and explanation, see Demanet, Notes de Physique Expérimentale (Louvain, 1905), t. iv. p. 8.—ED.
[5] "Nothing is created; nothing is lost"—ED.
[6] By isothermal diagram is meant the pattern or complex formed when the isothermal lines are arranged in curves of which the pressure is the ordinate and the volume the abscissa.—ED.
[7] Mr Preston thus puts it: "The law [of corresponding states] seems to be not quite, but very nearly true for these substances [i.e. the halogen derivatives of benzene]; but in the case of the other substances examined, the majority of these generalizations were either only roughly true or altogether departed from" (Theory of Heat, London, 1904, p. 514.)—ED.
[8] Methode avec retour en arriere.—ED
[9] Professor Soddy, in a paper read before the Royal Society on the 15th November 1906, warns experimenters against vacua created by charcoal cooled in liquid air (the method referred-to in the text), unless as much of the air as possible is first removed with a pump and replaced by some argon-free gas. According to him, neither helium nor argon is absorbed by charcoal. By the use of electrically-heated calcium, he claims to have produced an almost perfect vacuum.—ED.
[10] Another view, viz. that these inert gases are a kind of waste product of radioactive changes, is also gaining ground. The discovery of the radioactive mineral malacone, which gives off both helium and argon, goes to support this. See Messrs Ketchin and Winterson's paper on the subject at the Chemical Society, 18th October 1906.—ED.