June 19, 1913] 



NATURE 



4i. 



(/8) The water to which the specific gravity is 

 referred must be at some other definite temperature, 

 e.g. 6o° F., or possibly 4 C, the temperature of 

 maximum density. Thus, if 85 F. as before be the 

 standard temperature of the instrument and 6o° F. 

 that of the water, the specific gravity of the liquid 

 at 85 F. is referred to water at 6o° F. 



III. (a) The liquid to be tested must be at the 

 standard temperature of the instrument. 



03) The graduations are such that they give the 

 vaiue which would be found for the specific gravity 

 of the liquid if it were cooled or heated to some other 

 temperature and referred to water at that 2 tempera- 

 ture. Thus the standard temperature of the instru- 

 ment might be 85 F. The instrument would then 

 be used at 85 F., but the graduations on the instru- 

 ment would be such as to give the specific gravity 

 which would be found for the liquid if it were cooled 

 to 6o° F., and referred to water at 6o° F. 



The following table gives the specific gravities of 

 certain sugar solutions, as determined in accordance 

 with these various methods, assuming coefficients of 

 expansion as given in tables issued by the Kaiserliche 

 Normal Eichungs-Kommission of Berlin : — 



Watei 

 Solution A 



Specific gi 

 at s 5 K. ir 

 of water ; 



I 'OOOO 

 I '0496 

 I 'O9S9 



Specific gravity 

 at 85 F. in terms 

 of water at 6o° 



C9968 

 I '0462 

 I -09:4 

 1-1447 



OOOO 



•0500 

 •IOOO 

 •1500 



- Iii this case the liquid to lie at 85" when tested, but the instrument is to 

 give its specific gravity when cooled to 6o Q in terms of water at 6o°. 



Thus, taking solution C, and supposing in each case 

 the liquid is at 85 F., the instrument will float 

 immersed up to a definite division on the stem. In 

 method I. this division would be marked 1-1484, in 

 method II., 1-1447, an d in method III., 11500. 



Thus there would be a difference of i-6 degrees of 

 specific gravity between I. and III., and of 53 degrees 

 between II. and III., and it is clearly necessary to 

 specify the method of graduation. 



There is one obvious objection to the use of 

 method III. In order to graduate an instrument 

 correctly it is necessary to observe its immersion in 

 a liquid at the standard temperature, and then cal- 

 culate from a knowledge of the coefficient of thermal 

 expansion of the liquid and of its density at some 

 given temperature what its specific gravity at some 

 other temperature will be, and what mark therefore 

 should be put on the stem. No doubt tables could be 

 made up to do this for various liquids and tempera- 

 tures, but from the point of view of a standardising 

 institution it is preferable that the errors of graduation 

 which have to be determined in the case of instru- 

 ments sent for test should rest onlv on observations 

 made during the test and not on a knowledge of the 

 roefficient of expansion of the liquid in which the 

 instrument is to be used. 



The instrument is correctly graduated only for a 

 liquid having one definite coefficient of expansion, and 

 cannot be used without error for others. 



Of the other two methods, I. and II., method I. 

 has been the usual practice at Kew. The liquid under 

 test and the water to which it is referred are both 

 taken to be at the standard temperature of the instru- 

 ment, and this, in ordinary practice in England, is 



2 A fourth variation might be adrlftl by requiring that in this case the 

 water should not be at the temperature to which the liquid is cooled or 

 heated. 



NO. 2277. VOL. Qll 



about 6o°. No. II. has the advantage that the 

 reference temperature of the water is fixed and gives 

 results in agreement with the usual definition of 

 specific gravity, which assumes a fixed temperature 

 for the water. 



These notes are circulated with the view of eliciting 

 opinions from makers and users, and also of obtaining 

 information from other countries. 



The director of the National Physical Laboratory 

 will be glad to have an expression of opinion from 

 people interested in the subject. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 



Bristol. — On the nomination of the Society of 

 Merchant Venturers, in the college of which the faculty 

 of engineering of the University is provided and main- 

 tained, the council has appointed the Right Hon. 

 Sir William Mather, P.C., a member of the board 

 of that facultv, in succession to the late Sir William 

 H. White, KiC.B. 



Cambridge. — The following awards are announced : 

 Harkness Scholarship (geology) for 1913, J- M. 

 Wordie, St. John's College. Frank Smart prizes, J. 

 Line, Emmanuel College (botany); D. J. Gray, King's 

 College (zoologv). Wiltshire prize (mineralogy) for 

 1913, E. V. Appleton, St. John's College; honourable 

 mention, W. E. Evans, St. John's College. 



St. Andrews. — The Senatus Academicus has re- 

 solved to confer the honorary degree of LL.D. on 

 the following: — Lieut. -Col. Sir Chas. H. Bedford, 

 Dr. George Albert Boulenger, F.R.S., Mr. J. Balfour 

 Browne, K.C., Mr. F. Cornwallis Conybeare, Prof. 

 Herbert J. C. Grierson, and Prof. W. R. Hardie. 



The issue of the London University Gazette for 

 June 4 gives particulars of the advanced lectures in 

 scientific subjects which have been arranged during 

 the present month for students of the University and 

 others interested. Of those lectures which have still 

 to be delivered may be mentioned a special lecture on 

 the work of the Carnegie Nutrition Laboratory in 

 Boston, to be given in the Physiological Laboratorv 

 of the University, South Kensington, on June 20, at 

 5 p.m., by Prof. F. G. Benedict, director of the 

 Carnegie Laboratory. The admission to the lecture 

 is free, without ticket. 



The report of the council for the year 1913 to the 

 members of the City and Guilds of London Institute 

 provides full statistics and particulars of the subscrip- 

 tions and donations of the great City companies to 

 the institute since its inauguration. The total amount 

 given to the institute during thirty- four years for the 

 purposes of higher education reaches 889,139/. Three 

 of the companies — the Goldsmiths', Clothworkers', 

 and Fishmongers' — have each given above 120,000?. ; 

 eight others have each contributed above 20,000/., and 

 other five more than 10,000/. The most recent gift 

 is that of the Goldsmiths' Company towards the ex- 

 tension of the City and Guilds (Engineering) College, 

 which is incorporated in the Imperial College of 

 Science and Technology. During the year under 

 review the Goldsmiths' Company supplemented by 

 a further sum of 37,000/. its original gift of 50,000/.. 

 which was commented upon in the last report of the 

 council. 



The King Edward VII. British-German Founda- 

 tion, instituted by Sir Ernest Cassel, decided last 

 year to assist a number of young men of British 

 nationalitv to prosecute special studies in Germany 

 after the completion of their studies at one of the 

 British universities. The council of the British sec- 



