20 



farmyard manure has therefore been handed over to a non-profit- 

 making- syndicate — the Agricultural Development Company 

 (Pyrford) Ltd., the Chairman of which is Viscount Elveden, M.P., 

 and under these auspices the work is prog^ressing- favourably. 

 The results indicate that this is the be.^t method of bringing a new 

 discovery into practical use. 



The nature of the gas given off in the fermentation of straw 

 and Nile Sudd (papyrus stems) was studied in the Chemical 

 Department at the request of the Air Ministry. So long as air 

 was present, the gas obtained was carbon dioxide, but when the 

 air supply was cut off methane and hydrogen were obtained in 

 addition. The relative proportions of these two gases depended 

 on the reaction of the medium ; if it was kept neutral by means of 

 calcium carbonate there was a considerable quantity of methane 

 along with a certain amount of higher hydrocarbons ; if it became 

 acid the total evolution of gas was much diminished and the 

 methane largely disappeared, hydrogen being the chief constituent. 



The maximum production of methane was obtained at a 

 temperature of 35^-40° C. and in presence of some nitrogen com- 

 pound to serve as nutrient to the organisms. In these conditions 

 a yield of 4,400 cubic ft. of gas was obtained per ton of wheat 

 straw, and 9,400 cubic ft. per ton of Nile Sudd ; of this gas 38% 

 was carbon dioxide and 62% combustible gas made up of 56 parts 

 of methane and 6 of hydrogen. 



The maximum production of hydrogen was obtained when the 

 medium was allowed to become acid, but the total yield of gas 

 was then only l/30th that given under neutral conditions. 



EFFECTS OF MANURES ON THE COMPOSITION AND 

 QUALITY OF CROPS. 



Fertilisers affect the habit of growth and the quality of the 

 crop, but the changes, though recognisable by the practical expert, 

 are often so subtle that the chemist is as yet unable to characterise 

 them or to connect them up in any definite way with the chemical 

 composition. In the Rothamsted experiments the practical expert 

 is asked to grade the produce, and his reports are used by the 

 chemist in seeking to trace the chemical relationships. Malting 

 barley and potatoes are being studied in some detail. 



MALTING BARLEY. 



The experiments are carried out at 13 different centres as part 

 of the Research Scheme of the Institute of Brewing, and full 

 details are given in their Journal. The same seed and the same 

 manurial treatment are adopted at each centre. The yields are 

 given on p. 104. The samples of grain are valued by a committee 

 of expert buyers and are analysed by an experienced brewers' 

 chemist ; certain typical samples are separately malted by a 

 maltster. The results will show how quality is affected by 

 manurial treatment, soil and season ; in addition, it is hoped from 

 the data thus obtained to deduce chemical relationships which will 

 enable us to express better than at present the value or quality of 

 barley in chemical terms. The experiment began in 1922, one of 



