no 



POPULAR SCIENCE MONTHLY. 



'Insects and Disease — Malaria and Mos- 

 quitoes,' in which, after calling atten- 

 tion 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 de- 

 tail the connection existing between 

 mosquitoes and malaria. Nineteen spe- 

 cial 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 state- 

 ment 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 La- 

 veran discovered Plasmodium malariae, 

 and before exact experiment was pos- 

 sible, 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. 



The 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 aus- 

 pices of the German Chemical Society. 

 The original standard, proposed by Ber- 

 zelius, was the weight of the oxygen 

 atom taken as 100. This gave rise to 

 very large numbers, in the case of num- 

 bers 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 oxy- 

 gen atom was exactly sixteen times as 

 heavy as the hydrogen atom, this stand- 

 ard 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 recal- 



culation 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 indi- 

 rectly 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 pub- 

 lished advocating this new standard was 

 by Dr. F. P. Venable, of the University 

 of North Carolina, in 1888. Discussion 

 was particularly aroused in the Ger- 

 man 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 represent- 

 ing chemical societies of eleven coun- 

 tries (America, Belgium, Germany, Eng- 

 land, Holland, Japan, Italy, Austria, 

 Hungary, Sweden, Switzerland), showed 

 forty in favor of oxygen = 16, seven op- 

 posed, while two wanted both stand- 

 ards. Except one American, none were 

 opposed but Germans, and the German 

 vote was a tie between the two stand- 

 ards. The objections raised against us- 

 ing 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 be- 

 tween 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 inter- 

 national committee are making a vig- 

 orous protest against the decision of the 

 majority, it seems probable that this 

 decision will be concurred in by most 

 chemists throughout the world. 



