July 19, 1912] 



SCIENCE 



95 



One of the most interesting results is that 

 all organic eUorine compounds, with one or 

 two possible exceptions, have trivalent chlo- 

 rine. The formulas of such compounds will 

 need revision to take account of this fact. 

 Methyl chloride, if free valences do not exist, 

 would need to be written: HjC=ClH, which 

 would show at once why it dissociates so easily 

 into hydrochloric acid and methylene. Fluo- 

 rine is monovalent in fluorine compounds; 

 the other halogens have not been computed. 

 Sulfur is generally hexavalent, but in sulfur 

 dioxide it is quadrivalent. It is hexavalent 

 in carbon bisulphide. The formula might be: 



•%^ 



The fact that chlorine is trivalent in its 

 organic compounds confirms Drude's and Pas- 

 cal's deductions from a study of the refrac- 

 tivity, nonnal dispersion, and molecular mag- 

 netic susceptibility of these compounds. Pas- 

 cal found fluorine to be monovalent, chlorine 

 to be polyvalent. 



The fact that the cohesion is thus deter- 

 mined in part by the number of the valences, 

 and that a relationship, long ago ft)retold by 

 Laplace, is thus shown to exist between molec- 

 ular cohesion and refraction and dispersion of 

 light is of great interest. The formula 

 IPK=c{Wt. Val)V3 shows, on the elec- 

 tronic theory, that the electrons of the atoms 

 and those of the valences differ, and that they 

 can not be summed. Hence the cohesion is 

 proportional to their product, not to their 

 sum. This conception was the starting point 

 of Drude's reasoning concerning the influence 

 of valence on refraction and dispersion. The 

 general result of the establishment of this re- 

 lationship between valence and cohesion, be- 

 tween gravitational mass and cohesional 

 mass, between cohesion and light refraction, 

 and between cohesion and diamagnetie prop- 

 erties is, on the whole, to lend support to 

 Sutherland's view that molecular cohesion is 

 of a magnetic nature. The fourth power law 

 may possibly bear this out, as he urged. The 

 relation of intramolecular cohesion, or chem- 



ical affinity, and intermolecular cohesion is 

 also seen to be a very close one; and the latter 

 is apparently dependent upon the former. 

 Albert P. Mathews 

 IjNivEESirY OF Chicago, 

 May 18, 1912 



SOCIETIES AND ACADEMIES 



THE NEW YORK ACADEMY OP SCIENCES 

 SECTION OF biology 



At the regular meeting of the Section of Biol- 

 ogy, held at the College of the City of New York, 

 March 11, 1912, Chairman Frederic A. Lucas 

 presiding, the following papers were read: 



The Number and Kinds of Bacteria in City Dust: 

 C.-E. A. WiNSLOW and I. S. Kligler. 

 The authors presented the results of the exam- 

 ination of about 170 samples of dust from streets, 

 schools, houses and public buildings in New York. 

 The total numbers of bacteria found varied from 

 150,000 per gram to 145,000,000, averaging from 

 3,000,000 to 5,000,000 from the indoor dusts and 

 49,000,000 from the street dust. Spores made up 

 usually less than one tenth of the total. The 

 count obtained at body temperature was about half 

 that at room temperature, averaging from 2,000,000 

 to 3,000,000 per gram in the indoor dusts and 

 22,000,000 in the street dusts. B. coli was usually 

 present; in the street dust an average of 51,000 

 per gram was found and in two samples over 

 100,000, while none showed less than 100. The 

 indoor dust, on the other hand, showed an average 

 of between 1,000 and 2,000. Acid-forming strepto- 

 cocci, such as are characteristic of the mouth, were 

 present to the extent of over 1,000 per gram in 

 three fourths of the street samples and one half 

 of the indoor samples. The average for the street 

 samples was about 40,000 per gram; for the indoor 

 samples about 20,000 per gram. The large pro- 

 portion of these organisms, particularly in the 

 indoor dusts, appears to be significant of buccal 

 pollution. 



The Aerial Transmission of Disease: C. V. Chapin. 

 The diffusion of contagion through the room or 

 out of doors only was considered, not droplet in- 

 fection, which does not take place beyond a meter. 

 Bacteriological evidence was not discussed, though 

 the quantititative work of Winslow on sewer air 

 and spray infection was referred to, a work which 

 he is now extending to dust. Epidemiological 

 study and experiment have been rapidly narrowing 

 the list of alleged air-borne diseases. We now 



