February 25, 1909] 



NA TURU 



491 



.4 VLRE MILK SIFPLY. 



THE importance of a supply of pure and whole- 

 some milk can hardly be exaggerated, and 

 during the last few years much has been done to 

 ensure this by the education of the producer, and by 

 the formulation of regulations by the health authori- 

 ties. Contamination may take place at four stages : — 

 (i) the cow may be unhealthy, e.g. tuberculous; 

 (2) the condition of the farm and milkers and the 

 methods employed may be unsatisfactory ; {3) con- 

 tamination may take place in transit; or (4) during 

 <ir after sale to the consumer. 



In dealing with some phases of this subject, a 

 practical acquaintance with trade conditions is neces- 

 sary, or impracticable regulations may be imposed. 

 Thus, in a paper read by Mr. Primrose McConnell 

 before the Royal Society of Arts,' reference was made 

 to the exaggerated ideas of some sanitarians as to 

 the cubic and floor spaces required in the byres, and, 

 as the author remarked, if the ventilation is properly 

 arranged for, the mere air-space in a shed is a sub- 

 ordinate matter. 



The arm-chair sanitarian is apt to forget that one 

 milking has to be done in the early hours of the 

 morning — in winter in dark and cold — that disinfec- 

 tants, clean smocks, and hot water may be unat- 

 tainable luxuries, that in many cases all that can be 

 hoped for is the promulgation of the doctrine of 

 general cleanliness, and that to insist on liberal air- 

 space and various structural conditions in the cow- 

 sheds may mean an outlay which will render the 

 production of the milk too costly to give an adequate 

 return to the farmer. Far be it from the writer to 

 suggest that ideal conditions should not be formu- 

 lated and put into practice whenever possible, but in 

 all cases the regulations should be drawn up with the 

 help of trade experts, and with a due regard to the 

 conditions of the district. 



No doubt the conditions of supply which formerly 

 obtained, and perhaps to some extent still exist, in 

 some of the smaller farms are much to be deprecated, 

 but a great deal has been done, particularly by the 

 large dairv companies of the metropolis, to remedy 

 this. The problem of transit is still one that requires 

 much attention ; the ordinary milk churn is a dirt 

 and dust trap by which much contamination may be 

 introduced into the milk, and refrigerator vans need 

 to be provided by the railway companies. The 

 ordinary method of serving milk with a dipper, and 

 the manner in which milk in bowls is allowed to stand 

 on the counter by the smaller vendors amid a hetero- 

 geneous collection of other goods, are in urgent need 

 of alteration. 



To some statements made by Mr. McConnell in 

 the paper referred to the writer would take excep- 

 tion. Thus, the existence of large numbers of 

 microbes in milk, provided none was definitely patho- 

 genic, W'as considered to be of no importance. But 

 large numbers of microbes generally indicate dirty 

 production, which in its turn facilitates the entrance 

 of harmful bacteria. Moreover, milk swarming with 

 microbes may in some cases produce gastro-intestinal 

 disturbance. Tuberculin was considered to be of no 

 value, but veterinary authorities in all countries are 

 unanimous in regarding it as of the greatest value in 

 the detection of tuberculosis. The careful work of 

 the commissioners of the Royal Commission on Tuber- 

 culosis on the transmission of bovine tuberculosis to 

 man cannot be summarily dismissed by the statement 

 that '• their far-fetched experiments and tests have 

 not proved it to the satisfaction of many people who 

 understand the matter iust as well as thev do." 



R. T. H. 



1 " London Milk Supply from a Farmer's Point of View ' (Journ. Roy. 

 Soc. of Arts, December i8, 1908, p. 83). 



THE DEX.Siry OF GASES I\ REL.iTION TO 



THE .ITOMIC WEIGHT OF NITROGEN. 

 T^HE fourth and last instalment of the current 

 ^ volume of the well-known Geneva Society's 

 Transactions, referred to below,' has a special interest 

 for the chemist and physicist from the fact that it is 

 wholly made up of a series of communications from 

 the laboratory of chemical physics of the University 

 of Geneva under the direction of Prof. Ph. .\. Guye. 

 The memoirs, five in number, deal with experimental 

 researches on the physicochemical properties of certain 

 gases in relation to the revision of the atomic weight 

 of nitrogen, a problem which has occupied Prof. Guye 

 and his collaborators for some years past. The 

 greater number of the main results have alread)- been 

 seen in abstract in many serial publications. The 

 work before us contains the full memoirs, which are 

 illustrated by carefully executed drawings of the 

 apparatus employed. 



The respective titles are : — 



I. " Determination des Densit^s des Gaz anhydride 

 carbonique, Ammoniac et Protoxide d 'Azote par la M^lhode 

 du Volum^tre. " Ph. A. Guye et Al. Pintza. 



Annexe I. : " Contrdle des Densit^s de I'Oxygfene et de 

 I'Anhydride sulfureux." .\. Jaquerod et Al. Pintza. 



-Annexe II. : " Essai sur la Determination du Poids 

 atomique de I'.Azote par 1 'Analyse en Volume du Gaz 

 ammoniac." Ph. A. Guye et Al. Pintza. 



II. " Determination de la Density de I'Oxyde Azotique 

 par la M^thode des Ballons." Ph. .\. Guye et Ch. Davila. 



Annexe: "Density du Gaz acide chlorhydrique." Ph. 

 .\. Guye et G. Ter Gazarian. 



III. " Sur la Compressibility de quelques Gaz k O au- 

 dessous de PAtmosphfere. " A. Jaquerod et O. Scheuer. 



IV. " Determination des Pressions et Temperatures 

 critiques de quelques Gaz." E. Briner. 



y. " Resume general." Ph. A. Guye. 

 The main results may be thus stated : — ■ 

 The weights of the normal litre, that is, the weights 

 of a litre of the respective gases at o°, under a pressure 

 of I atmosphere at sea level, under the latitude of 45°, 

 are as follows : — 



Caibon dioxide ... 

 Ammonia 

 Nitrous oxide 

 Oxygen ... ... 



Sulphur dioxide... 

 Nitric oxide 

 Hydrogen chloride 



1-9768 

 07708 

 1-9777 



1 -4292 



2 9266 

 1-3402 

 1-6398 



For the values of compressibility and critical con- 

 stants of these gases, as well as of those of certain 

 methyl derivatives, we must refer to the original 

 memoirs. 



The bearing of the observations so far as they are 

 applicable to the question of the atomic weight of 

 nitrogen is discussed by Prof. Guye in an introductory 

 communication. The result is to show that Stas's 

 value of 1404 is probably too high, as has been shown, 

 independently by Gray. The most probable value is 

 1401, a number already adopted by the International 

 Committee on .Atomic Weights in its last report. 



EDUCATION AND EMPLOYMENT. 



WE are glad to see that attention is being again 

 directed to problems of the relation betvi-een 

 education and national welfare. In his address as 

 president of the .Association of Technical Institutions, 

 last year, .Sir Norman Lockyer referred to the 

 deplorable national w-astage that goes on after 

 children leave the primary school, and pointed out 

 that by permitting the half-time system the State is 



1 •' Mimoires de la SocielcdePhysiqueet d'Histoirenaturellede Geneve," 

 vol. XXXV., Fascicule 4, JJecember. (Geneve : Georg et Cie., 1908.) 



NO. 2052, VOL. 79] 



