3So 



NAIURE 



[February i6, 1893 



purposes of Koch's and Hansen's processes is also discussed. It 

 is obvious that the organisms to be feared in a brewery are those 

 which will flourish in wort or beer, and that the mere knowledge 

 of the number of bacteria in any given water as revealed by 

 gelatine plate cultures is but of little use. Hence Hansen and 

 his pupils reject for such examinations gelatine-peptone, substitut- 

 ing sterilised wort and beer as a culture material. An interesting 

 table is given showing the different bacteriological results obtained 

 in the use of gelatine-peptone, gelatine to which wort had been 

 added, wort alone, and beer. For example, whereas a particu- 

 lar brewing-water yielded by gelatine-peptone about 8000 

 colonies per c.c, the majority of which were bacteria ; gelatine 

 mixedwith wortgaveabouti4, allbeingmoulds ; in wort5'4were 

 found, consisting of bacteria and moulds, whilst sterilised beer 

 gave only o*8 for the c.c, and only moulds. Holm points out 

 that to estimate the value of a water for brewing purposes a note 

 should also be made of the rate at which the organisms develop 

 in the wort or beer, for should signs of growth only declare 

 themselves after four or five days in the laboratory under favour- 

 able conditions of temperature and in the absence of competing 

 forms, it is not unnatural to expect that their vitality, under the 

 more rigorous conditions imposed during brewing operations, 

 would be so far impaired that their development, if taking place 

 at all, would only be accomplished with great difficulty. Although 

 instances occurred in which even after the lapse of seven days 

 growths first made their appearance, yet in the majority of cases 

 the incubation of the wort-flasks for one week was sufficient. 

 Holm is of opinion that the use of other culture materials besides 

 •wort is unnecessary, as all the organisms which successfully develop 

 an beer can also grow in wort. Moreover, it was found that in 

 the process of sterilisation to which the beer was submitted a 

 considerable proportion of its alcohol was lost, thus diminishing 

 its natural bactericidal properties, A beer containing 5 to 6 

 percent, of alcohol, after sterilisation, had this reduced to 28 

 per cent., although it even then proved a very unfavourable 

 medium for the development of ordinary water bacteria. As a 

 practical outcome of his experiments Holm emphasises the 

 necessity of a careful selection of the site for the erection of the 

 water-reservoir attached to a brewery. The reservoirs of the 

 old brewery at Carlsberg are placed in the immediate vicinity of 

 the storehouses for grain and malt, consequently in this water a 

 far largernumber of moulds were met with than in the water ex- 

 amined from differently situated reservoirs supplying the labo- 

 ratory and another brewery. But although moulds usually 

 predominate, yet they are not so much to be feared as the bac- 

 teria, more especially those which are found in the fermentation 

 chamber, for although they are unable to assert themselves to 

 any considerable extent in the beer preserved in the store cellar, 

 yet when it is drawn off and thus aerated, and the temperature 

 raised by its transference to bottles or small casks, these organ- 

 isms can develop with an astonishing rapidity, and produce 

 great mischief. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 



Cambridge. — Dr. Shore, of St. John's College, late Ex- 

 aminer in Physiology, has been elected a member ot the Special 

 Board for Medicine; Dr. A. Macalister, F.R.S., St. John's, 

 has been appointed an elector to the Professorship of Chemistry ; 

 Dr. Ferrers, F.R.S,, Master of Gonville and Caius, an elector 

 to the Plumian Professorship of Astronomy ; Prof. Newton, 

 F.R.S., Magdalene, an elector to the Professorship of Anatomy ; 

 Dr. Phear, Master of Emmanuel, an elector to the Professorship 

 of Botany ; Dr. R. D. Roberts, Clare, an elector to the Wood- 

 wardian Professorship of Geology ; Mr. P. T. Main, St. John's, 

 an elector to the Jacksonian Professorship of Chemistry, &c. ; 

 Mr. R. T. Glazebrook, F.R.S., Trinity, an elector to the Pro- 

 fessorship of Mineralogy; Mr. F. Darwin, F.R. S., Reader in 

 Botany, an elector to the Professorship of Zoology and Com- 

 parative Anatomy; Mr. W. D. Niven, F. R.S., Trinity, an 

 elector to the Cavendish Professorship of Physics ; Dr. Phear, 

 an elector to the Professorship of Mechanism ; Prof. Liveing, 

 F.R. S., St. John's, an elector to the Downing Professorship of 

 Medicine; Dr. P. H. Pye-Smith, F.R.S., an elector to the 

 Professorship of Physiology ; and Sir G. M, Humphry, F.R.S., 

 an elector to the Professorship of Pathology. 



NO. 1216, VOL. 47] 



SCIENTIFIC SERIALS. 



American Journal of Science, February. — Isothermals, iso-- 

 piestics, and isometrics relative to viscosity, by C. Barus. The 

 substance experimented upon was marine glue, and its viscosity 

 at different pressures and temperatures was measured by a trans- 

 piration method, the substance being forced through steel tubes 

 10 cm. long and 0*5 to i cm. in diameter under pressures as 

 high as 2000 atmospheres. It was found that in proportion as 

 the viscosity of a body increases with fall of temperature, its 

 isothermal rate of increase with pressure also increases. Speaking 

 approximately, the rate at which viscosity increases with pres- 

 sure at any temperature is proportional to the initial viscosity 

 at that temperature, and, conversely, the rate of decrease with 

 temperature is proportional to the actual temperature and inde- 

 pendent of the pressure. An interesting result is that in high 

 pressure phenomena at least 200 atmospheres must be allowed 

 per degree Centigrade, in order that there may be no change of 

 viscosity. — "Potential," a Bernoullian term, by Geo. F. 

 Becker. — Datolite from Loughboro, Ontario, by L. V. Pirsson. 

 —A new machine for cutting and grinding thin sections of rocks 

 and minerals, by G. H. Williams. — Stannile and some of the 

 alteration products from the Black Hills, S.D., by W. P. 

 Headden. — Occurrence of hematite and martite iron ores in 

 Mexico, by R. T. Hill, with notes on the associated igneous 

 rocks, by W. Cross. — Ca;sium lead and potassium-lead halides, 

 by N. L. Wells. — Ceratops beds of Converse County, 

 Wyoming, by J. B. Hatcher.— Use of planes and knife-edges in 

 pendulums for gravity measurements, by T. C. Mendenhall. 

 The employment of a pendulum to which the plane is attached 

 instead of the knife-edge presents several advantages. The 

 plane jnay be accurately adjusted at right angles to the rod by 

 simple optical methods. A pendulum carrying a plane instead 

 of a knife-edge is vastly less liable to injury, and the knife-edge 

 being no longer an integral part of the vibrating mass can be 

 reground or replaced at will. The length of the pendulum is 

 more capable of accurate determination, since the error intro- 

 duced by the yielding of the edge under pressure is eliminated. 

 The disadvantage due to the uncertain position of the axis of 

 oscillation can be mechanically got rid of by a proper construc- 

 tion of the raising and lowering apparatus, and experiment 

 shows that the period in the course of twelve sets of swings of 

 an hour each does not vary by as much as one part in a million. 

 The best angle for the knife-edge was found to be about 130°, 

 the material used being agate. — Preliminary note on the colours 

 of cloudy condensation, by C. Barus. If saturated steam is 

 allowed to pass suddenly from a higher to a lower temperature 

 in uniformly temperatured, uniformly dusty air, a succession of 

 colours is seen by transmitted white light which, taken in in- 

 verse order, are absolutely identical with the colours of Newton's 

 rings of the first two orders. — Lines of structure in the Winne- 

 bago Co. meteorites and in other meteorites, by H. A. 

 Newton (reprinted in this issue). — Preliminary note of a new 

 meteorite from Japan, by Henry A. Ward. — Restoration of 

 Anchisaurus, by O. C. Marsh (see Note, p. 349). 



American Journal of Mathematics, vol. xiv. No. 4 (Balti- 

 more, 1892). — The main object of the note on the use of supple- 

 mentary curves in isogonal transformation, by R, A. Harris 

 (pp. 291-300), is to show how the problem ofrepresenting one 

 plane conformably upon another, using any real function of the 

 variable, may be made to depend upon the problem of con- 

 structing supplementary curves fiom given tracings of the corre- 

 sponding principal curves. It is well illustrated by four carefully 

 drawn figures. In her memoir (pp. 301-325) on the higher 

 singularities of plane curves. Miss C. A. Scott goes over ground 

 to some extent previously occupied by Profs. Cayley and H. J. 

 S. Smith in writing on the same subject (cf. also papers by 

 Brill and Nother in \.\\e.Math, Annalen, vols. ix. xvi. xxiii,). 

 Nother's results are presented in analytical form, "involving no 

 dependence on geometrical ideas even when geometrical terms 

 are used." The author brings out his results more clearly by 

 making use of Dr. Hirst's method of quadric inversion. The text 

 is accompanied by twenty-seven drawings of curves. Mr. W. H. 

 Metzler, writing on the roots of matrices (pp. 326-377), employs 

 a modification of Dr. Forsyth's method of proving Cayley's 

 " identical equation" (" Messr. of Mathematics," vol. xiii.) to 

 prove Sylvester's law of latency and Sylvester's theorems. He 

 also investigates the existence of roots of matrices for different 

 indices, and in particular the roots of nilpotent matrices. A 



