Page:Popular Science Monthly Volume 58.djvu/118

110 'Insects and Disease—Malaria and Mosquitoes,' in which, after calling attention to the then recent researches of Dr. Patrick Manson, in China, and others, proving that the mosquito acts as an intermediary host of Filaria sanguinas hominis, he proceeds to point out in detail the connection existing between mosquitoes and malaria. Nineteen special arguments are marshaled, several of which deserve consideration at the present time. Among the points urged by Dr. King is the fact that malaria is prevented by mosquito nets, a statement being quoted to the effect that "on surrounding the head with a gauze veil or conopeum the action of malaria is prevented and that thus it is possible to sleep in the most pernicious parts of Italy without hazard of fever." This was, of course, written long before Laveran discovered Plasmodium malariæ, and before exact experiment was possible, but Dr. King deserves much credit for bringing together so much evidence in favor of a theory the correctness of which could only be demonstrated twenty-seven years later.

proper standard for atomic weights has occasioned controversies among chemists for nearly a century, but at last bids fair to be settled, through the practical agreement of an international committee, under the auspices of the German Chemical Society. The original standard, proposed by Berzelius, was the weight of the oxygen atom taken as 100. This gave rise to very large numbers, in the case of numbers with high atomic weights, and gradually the use of hydrogen = 1 came to supersede that of oxygen = 100. So long as it was assumed that the oxygen atom was exactly sixteen times as heavy as the hydrogen atom, this standard was satisfactory. With increasing refinement of analytical work, it began to appear that the atomic weight of oxygen, with reference to hydrogen, was slightly less than sixteen. For some time the exact figure was supposed to be 15.96. This necessitated a recalculation of the atomic weights of all the elements, for they are for the most part determined with reference directly to oxygen or chlorin, and only indirectly with reference to hydrogen. As it was certain that the final word had not been said as to the atomic weight of oxygen, the suggestion was made by a few chemists to use as a standard oxygen = 16. The first article published advocating this new standard was by Dr. F. P. Venable, of the University of North Carolina, in 1888. Discussion was particularly aroused in the German Chemical Society by Professor Brauner, of Prague, who was strongly supported by Ostwald and opposed by Meyer and by Seubert. The latter, who is one of the great authorities on atomic weights, has since come to the support of oxygen = 16. The recent report of an international committee representing chemical societies of eleven countries (America, Belgium, Germany, England, Holland, Japan, Italy, Austria, Hungary, Sweden, Switzerland), showed forty in favor of oxygen = 16, seven opposed, while two wanted both standards. Except one American, none were opposed but Germans, and the German vote was a tie between the two standards. The objections raised against using oxygen = 16 as a standard seem to be solely from a didactic standpoint, in having something other than unity as a standard. It was clearly pointed out by Dr. Venable in his second paper that there was no necessary connection between the standard and unity. Some objectors would take oxygen as unity, but this would be impracticable, as it would make such radical changes in the numbers now in use. An additional reason for the newer standard is that a large proportion of those weights most frequently used approach very closely to whole numbers, a point of no slight advantage to the technical chemist. While the small minority of the international committee are making a vigorous protest against the decision of the majority, it seems probable that this decision will be concurred in by most chemists throughout the world.