554 



NA TURE 



[October 4, 1894 



'ince it gave a deflection of two-thirds of a millimetre for a 

 milligram. The weight of the suspended body was Ijj'jiogr., 

 and the loss of weight in the solutions was always over 129 gr., 

 so thai the thread was not required to support more than 4 gr. 

 The loss of weight in pure water was I29'i94gr. at 17 soC, 

 and did not vary by more than oo32 gr. in five months. The 

 diflerencc in the individual numbers for the loss of weight in 

 any given liquid was 01 1 mg. on the average, which corre- 

 sponds to about a millionth of the density to be determined. 

 These very accurate determinations brought out some interest- 

 ing details with regard to the "molecular volumes" of the 

 sub>tances in solution. Phosphoric and sulphuric acids showed 

 a decided diminution of this volume at extreme dilutions, while 

 sugar, hydrochloric and acetic acid, and sodium chloride and 

 carbonate did not show this diminution. 



The Annates ae Chimit tt dc Piiynqm for September con- 

 tains a paper, by M. Henri Bagard, on the thermoelectric force 

 between two electrolytes, and on the Thomson effect in the case 

 of electrolytes. The paper contains a very complete history of 

 the work which has been done on this subject. ' The author 

 uses a number of thermoelectric junctions joined in series, and 

 measures the electromotive force developed by a given differ- 

 ence in temperature between the hot and cold ^urfaces of 

 separation between the electrolytes by means of a capillary 

 electrometer. This electrometer was capable of indicating an 

 electromotive fo.'ce of one-hundrei-thousanJth of a volt. In 

 order to check the diflTusion which takes place at the common 

 surface of the electrolytes, the author uses a porous membrane. 

 By using membranes composed of such different substances as 

 goldbeater's skin and vegetable parchment, it was proved that 

 Ihe membrane had no eflect on the electromotive force, except 

 to cause it to diminish slightly with lime. Thus Ihe results 

 obtained with a membrane are probably identical with what 

 would be obtained could observations be made without a mem- 

 brane, and without diffusion and convection currents being set 

 up through the surface of separation. Observations were taken 

 both while the temperature of one junction was rising and again 

 when cooling. The points obtained during the second of these 

 operations often fell below the curve given by the previous set. 

 This effect, which never amounted to a difference of ^^},t,t, volt, 

 the author considers to have been entirely due to diffusion. 

 Thermoelectric couple;, consisting of solutions of two different 

 salts, and of solutions of the same salt but of different concen- 

 tration, were examined, and the results obtained are shown by 

 means of curves. In order to examine the Peltier and Thomson 

 effects in ihc case of electrolytes, small bolonclers were em- 

 ployed to measure the change in temperature. The important 

 fact that the Peltier effect is of opposiie sign on opposite sides 

 of the neutral point was amply verified, and it appears that the 

 change of sign takes place at the neutral point. In all cases 

 the thermoelectric phenomena, the Peltier effect and the 

 Thornton eflect gave results in the case of electrolytes similar to 

 ihoM obtained with metals. 



" Creameries and Infectious Diseases " is the title of asbort 

 paper which I)r- Welply has had reprinted from the Lancet. 

 It u a m»t u<eful little pamphlet, inasmuch as it calls attention 

 to a danger which, 10 far, has escaped public notice. Cream- 

 rrie<i receive, a« is well known, their milk from a number of 

 farms : but after the cream has b:en removed, some of the skim 

 or separated milk is lent back to the farms, where it is con- 

 sumed in various ways. The milk received from the various 

 farms is all mixed together, and thus it is not difficult to see 

 how one caseuf typhoid fever, or some other illness on one of 

 these farms, may not only infect the creamery, but may, by 

 means of the separated milk, infect the whole group of dairies 

 supplying this creamery, thus starting an indefinite number of 



NO. 1301, VOL. 50] 



fresh disease centres. Dr. Welply describes an outbreak of 

 typhoid fever which he traced to a creamery, and to the use of 

 food or milk from dames which became infected secondarily. 

 In several of the dairies which he visited, he states that he 

 found the dair^'-maids acting in the dual capacity of milkers 

 and nurses, and he is distinctly of opinion that the contagium got 

 into the milk from the hands of the dairy-maids. It is clear 

 that unless we can obtain stringent regulations pissed, such as 

 are in use in Denmark, Sweden, and Germany, and which our 

 Board of Agriculture have published in their reports on dairy 

 farming in these countries, unless we can procure similar legis- 

 lative measures, cooperative dairy farming in England will 

 always remain a continual source of danger to the public 

 health. Dr. Welply says " it would be wise at all tinnes to boil 

 separated milk when used as an article of human diet " ; we 

 would go still farther, and say that It is undesirable to drink 

 any milk which has not been previously thoroughly boiled, not 

 w.Trmed or brought to the boil, but boiled for several minutes. 

 The National Health Society took this question up some years 

 ago, and issued a short leaflet on the advisability of boiling all 

 milk before use. 



LuF.RSSEN AND Haenlein's Bii'.iothtia Boliinica will in 

 future be edited by Prof. C. Luerssen and Prof. B. Frank. 



Messrs. Blackie and Son have just issued part 6 of Prof. 

 Oliver's translation of Prof. Kerner's " Natural History of 

 Plants." 



Wk have received the Calendars for the Session 1S94-5, of 

 the University College, Bristol, the Durham College of Science. 

 Xewcastle-upon-Tyne, and the Merchant Venturers' Technical 

 College, Bristol. 



The Cleneral Report on the Operations of the Survey of 

 India Department for 1S92-93 has just been issued from the 

 office of the Superintendent of Government Printing, Calcutta. 



The June number of Timehri, the journal of the Royal 

 .Vgricultural and Commercial Society of British Guiana, has just 

 come to hand, and contains, as usual, a number of very varied 

 and interesting papers, notably, "The Guiana Orchids," by the 

 editor — James Rodway ; "Late Rainfalls, some of their Kllects," 

 by James Gdlespie; and "Some Enemies of our Canefields," by 

 S. R. Cochran. The society celebrated the fiftieth year of its 

 existence in March of this year, when a successful hisloric.il 

 exhibition was held in honour of the event. 



The sixteenih annual meeting of the Greenock Natural 

 History Society was held on September 28, Mr. T. L. 

 Patterson, president, occupying the chair. During the session 

 1S93-94 seven papers were read, \\i, : "The Sorghum Sugar 

 Experiments in the United Stales," by Mr. T. L. Patterson ; " .\ 

 Study of Fungi," by Dr. M. Calder ; " Scenes from Australia.' 

 by Mr. Thomas Steel ; " Gems and Precious Stones," by Mr. 

 James M'Neil ; "The Evolution of Navigation and Nautical 

 Astronomy," by Mr. G. W. Niven ; " Plants with Angular 

 Stems," by Mr. John Ballantyne, Rothesay; "Notes on the 

 Cladoccra," by Mr. M. F. Dunlop. 



"Science is measurement." Mr. J. Lawrence, of %(t 

 Fulham Road, London, evidently believes that the converse of 

 this is true, for he has sent us a " Tell-tale " milkjug, which 

 London milkmen will probably regard with sorrowlul feelings. 

 The object of the jug is to furnish householders with a standard 

 wherewith to judge the probity of their dairymen. The jug is 

 a glass measure graduated at every quarter-pint. Below each 

 pint and half-pint mark three lines are etched showing lli- 

 tliickne-s of cream which should appear in milk of avcr.it;i 

 c|uality, in milk of good qualiiy, and in milk of very good 

 quality after the lii|uid has been allowed to stand (or a time. 

 liolli the quantity and the quality of the milk can thus be 

 easily tested. 



