638 



SCIENCE 



[N. S. Vol. XXXVIII. No. 983 



Potassium cyanide solution is a solvent for 

 copper and was used as sucli and as an etching 

 medium iu the study of copper-clad steels. 



C. E. Kenneth Mees, D.Sc. : The Physical Chem- 

 istry of Photographic Development. 

 Photographic development depends on the fact 

 that certain reducing agents can reduce grains of 

 emulsified silver bromide which have been exposed 

 to light, but not grains which have not been exposed 

 to light. 



The function of exposure is to produce a nucleus 

 which enables silver to be precipitated with a lower 

 reduction potential of the developer than would 

 be necessary if no nucleus were present. 



The energy required to produce this nucleus is 

 so small that only one or two molecules per grain 

 can be affected by the exposure. 



The velocity of development follows the com- 

 mon type of equation for a monomolecular reac- 

 tion, derived from the surface as the variable; it is 

 conditioned chiefly by diffusion processes. 



Bernakd C. Hesse : The Patent Expert and the 

 Chemical Manufacturer. 



Comparison of the general practise of Ameri- 

 can chemical manufacturers, in regard to patent- 

 able inventions, with European practise, shows 

 that the latter provides for more care in exami- 

 nation of the prior art, in the preparation and 

 prosecution of the specification and in the pro- 

 tection of rights under a granted patent than 

 does the former. 



The manifold advantages of having a patent 

 expert, better called a patent chemist, primarily 

 charged with the responsibility of attending to 

 the above important details as well as iu acting 

 as a connecting link between the principal, the 

 inventor, the counsel and the patent office are par- 

 ticularly emphasized and their advantages illus- 

 trated by reference to some actual eases; further 

 duties, such as systematic watch over progress in 

 the art, in general, as well as in the particular 

 field of the principal and for his benefit, are also 

 pointed put. The patent chemist may or may not 

 be an integral part of the working staff, but he 

 should be called upon at every new manufactur- 

 ing or other step on the part of the principal. 

 Henet Leefman: In Commemoration of the Cen- 

 tennial of the Publication of the Berzelian 

 System of Symbols. Will be published in 

 Jour. Amer. Chem. Soc. 



George A. Soper: The Utilization of Sewage. 

 The authorities charged with the making of 



plans for the disposal of sewage are frequently 

 met by a public demand that the sewage shall be 

 used as fertilizer. The belief that a large manur- 

 ial value can be recovered is based upon the 

 former belief of scientists and has been kept 

 alive by novelists and other misguided persons. 

 The fact is that the manurial value of sewage has 

 been greatly overestimated. Sewage contains use- 

 ful fertilizing ingredients, but experience shows 

 that, like the gold in sea water, it costs more to 

 extract them than they are worth. 



Sewage works which are capable of utilizing 

 the manurial ingredients are of two classes: 

 First, those in which the sewage is applied di- 

 rectly to land, as in agriculture, and, second, 

 those in which the utilizable ingredients ai'e ex- 

 tracted by mechanical means, such as screening 

 and sedimentation. Neither process has thus far 

 proved profitable. 



In the sanitary disposal of sewage, the manage- 

 ment of the settleable impurities termed sludge is 

 considered to be the point of central difficulty. 

 In order to extract the manurial ingredients in 

 sewage, it will be necessary to devise some method 

 for the production of denser sludge than is now 

 obtainable and a satisfactory process for the 

 further concentration of the solid matters in the 

 sludge should be looked for. 



All recent contributions of science to the art of 

 sewage disposal have been directed almost exclu- 

 sively to the disposal of the wastes without of- 

 fense and as little expense as possible, the idea 

 being to get rid of the sewage and not to attempt 

 to make use of its manurial value. 



DIVISION OF AGEICULTURAL AND POOD CHEMISTRY 



H. E. Barnard, Chairman 



Glen F. Mason, Secretary 



H. E. Barnard: Laboratory Control of the Food 



Industry. 



The chemist is the technical adviser of the food 

 manufacturer, both on practical questions that 

 come up in the course of daily operations and on 

 all points having to do with food laws. The 

 canner and packer are just realizing that their in- 

 dustry is a technical, not a rule-of -thumb business 

 and are establishing central laboratories in which 

 much of the construction work in industry is being 

 done. 

 F. C. Cook : Bouillon Cubes. 



Ten samples of cubes collected on the New York 

 market in the summer of 1912 were analyzed, with 

 the following results: 



