v
snbsequent research. His "law " of boiling poiuts is no longer
regarded as an accurate expression of experimental facts, and his
deductions with respect to specific volumes have been largely affected
by snbsequent work. It has been couclusively shown that molecular
volume is not a purely additive property. There is no longer room
for doubt that the molecular volumes of substances are affected by
far more conditions than Kopp was able to take cognisance of.
The value CH2 =22 has no other signiflcance than as expressing the average increment in volume in successive members of a homo- logous series donbtful whether even this meau value is correct. Indeed, as the physical data increase, it becomes Later observations appear to show that the value augments as the series is ascended The relation C= 2H no longer applies to carbon compounds in general. What is true of carbon and hydrogen is equally true of oxygen, whether as carbonyl- or as hydroxyl-oxygen. No definite or uniform values can be assigned to oxygen such that the molecular volume of a liquid cau be a priori determined. The valnes given by Kopp are simply mean values, but the actnal volumes are affected by conditions of which, as yet, we have no very precise knowledge or any certain means of measuriug. The values for the other elements are, of course, affected by these cousiderations. Thus the specific volume of chlorine is obtained on the assumption that the values for carbon and hydrogen are constant. All, then, tends to show that the molecular volume is not the sum of constant atomic volumes.
Althongh Kopp's theoretical conclusions hardly admit of the generality which he assumed them to possess, his experimental work remains unassailed and unassailable, a monument to lhis ingenuity, manipulative skill, his rigid seuse of accuracy, and illimitable patience. Т. Е. Т.
Dr. JoHN RAE, LL.D. (Edin.), a traveller in Arctic America, of extraordinary energy and endurance, a keen observer of Nature, aud the discoverer of the fate of the Franklin expedition, was born in Orkney in 1813, died in London in 1893, and is buried in the cathedral of St. Magnus at Kirkwall, where a statue is erected to his memory
He qualified as a surgeon in Edinburgh, and as such he accompanied one of the ships of the Hudson's Bay Company, whose service he joined, and then for ten years he resided at Moose Factory. (1) His first journey of pure exploration was a boat voyage along the coast of Hudson's Bay to Repulse Bay, where he wintered, and, in the following year he surveyed a coast line of 700 miles, conneeting the surveys of Ross in Boothia with those of Parry at Fury and Heckla Strait. (2) Noxt he joined the expedition of Sir J. Richard
