146 



SCIENCE 



[N. S. Vol. XLVI. No. 1180 



method is shown to be highly empirical, the errors 

 being produced by decomposition of the oxalic 

 acid by the action of the light in the presence of 

 manganese salts. A modified ferrous sulfate 

 method is accurate and is recommended for fac- 

 tory control work. The latter method gives re- 

 sults in close agreement with results obtained by 

 Bimsen 's distillation , method and a new direct 

 iodimetrie method worked out by the author. 



Some relations of the effect of over-heating to 

 certain physical and chemical properties of as- 

 phalts: A. W. HixsoN and Harold E. Hands. An 

 oil asphaltic cement, a brick fQler fluxed with an 

 asphaltic oil residuum and a crude Trinidad 

 asphalt were heated to various temperatures be- 

 tween 163° C. and 350° C. under uniform condi- 

 tions. Physical and chemical analyses were made 

 on the products of the various heatings. The re- 

 sults show that heating asphalts above certain 

 temperatures change both the physical and chem- 

 ical properties. The carbene content was not 

 changed materially until the temperature of heat- 

 ing was above 200° C. Above that temperature 

 there was a decided increase in oarbenes. The re- 

 sults seem to indicate that earbenes are the result 

 of cracking paraffine and asphaltic hydrocarbons 

 into napthenes and unsaturated hydrocarbons. 

 Moderate heating may so change the nature of the 

 asphalts as to render them more soluble in carbon 

 tetrachloride than in carbon disulphide. Over- 

 heating causes marked changes in natural and oil 

 asphalts which render them unfit for many struc- 

 tural purposes. Two hundred and thirty-five de- 

 grees Centigrade is probably the maximum tem- 

 perature to which an asphalt may be heated with- 

 out permanent injuries to its useful properties and 

 for certain structural purposes they should not be 

 heated above 200° C. It is believed that the fixed 

 carbon content when corrected to the original 

 weight before heating offers a means of tracing 

 the changes in the molecular structure of the hy- 

 drocarbons when they are subjected to the influ- 

 ence of heat. There is a close relation between 

 the carbene value and the physical and chemical 

 properties of asphaltic materials. The carbene 

 specification is important for asphaltic materials 

 for construction purposes. 



Chemical Industry iji Canada: H. E. Howe. 

 The paper outlined something of the chemical in- 

 dustry in Canada, with special reference to recent 

 important developments and new processes which 

 have been perfected under the stimulating influ- 

 ence of war conditions, but which will become im- 

 portant factors in the chemical business after the 



war. It also recounted something of the natural 

 resources of Canada as indicating the raw mate- 

 rials upon which chemical processes and industries 

 may eventually be based, concluding with the state- 

 ment of the steps that are being taken by private 

 corporations, educational institutions and the gov- 

 ernment to apply scientiflc and industrial research 

 looking toward the more economic utilization of 

 natural resources and the establishment of chem- 

 ical industries to serve a population which will 

 undoubtedly increase at an abnormal rate follow- 

 ing the declaration of peace. 



The availatility of nitrogen in fertilisers. A 

 new method tased on the nitrogen rendered water- 

 soluble by incubation with a fertile soil: J. P. 

 ScHEOEDER. Theoretical and practical considera- 

 tions governing the availability of substances for 

 plant nutrition in recent researches dealing with 

 the assimilation of various forms of nitrogen and 

 the merits of various methods for determining 

 availability were discussed. A proposed method 

 consists of incubating a small sample of fertilizer 

 with a 100 gm. portion of fertile soil at 30° C, 

 maintained just below its critical moisture con- 

 tent and determining the total nitrogen that has 

 been converted into the water-soluble form. It 

 differs from the nitrification method and the am- 

 monification method in that it takes into considera- 

 tion both of those forms of nitrogen; also that in 

 the form of nitrites and soluble protein compounds, 

 all of which are assumed to be available or readily 

 convertible into available form. It makes pos- 

 sible a shorter incubation period than in the nitri- 

 fication method and the use of the exact ammonia 

 determination instead of the diificult nitrate esti- 

 mation. 



The fertilizer value of city wastes — II., garbage 

 tankage: J. P. Scheoedek. The origin and compo- 

 sition and principal methods of rendering garbage 

 were briefly outlined. Complete analyses of twenty 

 samples of garbage tankage, representing all the 

 larger garbage reduction plants in operation in 

 this country, show on the average 3.3 per cent, am- 

 monia, 7.84 per cent, bone phosphate and 0.80 per 

 cent, potash, after removal of the oil, which usually 

 amounts to about 12 per cent. Calculations based 

 on these analyses and on figures shovring produc- 

 tion in cities of 50,000 and over, call attention to 

 the large source of ammonia available. The availa- 

 bility of this ammonia for plant use is shown by 

 experiments with different methods, and the gen- 

 eral applicability of the material for fertilizer pur- 

 poses based on its physical and chemical proper- 

 ties was discussed. 



