NA TURE 



{Nov. 25, 1S80 



In the same journal M. de la Source describes his experiments 

 on the dialysis of ferric oxide dissolved in a solution of 

 ferric chloride. " Fer Bravais " of medicine consists of 

 SoFcgO^ . FejClg ; after three months' dialysis of a dilute solu- 

 tion of this substance the greater part of the chlorine had passed 

 into the dyalysate, the proportion of ferric oxide to chloride was 

 •then il6Fe;03 . FejCl|3, and the chlorine yet continued to pas; 

 through the dialyser. The author thinks that ferric hydrate is, 

 J>ir St; under certain conditions soluble in water. 



Herr a. IIerzen describes in Die./. Ccntralblatt some ex- 

 periments on acetous fermentation. In each of three flasks was 

 placed 100 c.c. pure water: to the first flask 10 per cent, pure 

 alcohol and a drop from the surface of a fermenting wine full 

 of Mycodenna accti were added ; to the second flask were added 

 5 per cent, of pure acetic acid and a drop of the fermenting 

 \-. ine ; and to the third flask were added 5 per cent, acetic acid, 

 _5 per cent, of a saturated solution of boric acid, and a drop of 

 the fermenting wine. After eight days at 25° no Mycod/yuui 

 appeared in the first flask, much appeared in the second, and a 

 little in the third. Hence the author concludes that Mycodenna 

 aceti lives at the expense of acetic acid already formed in wine, 

 and that it does not cause the transformation of alcohol into 

 acetic acid, but that it is rather a consequence of this chemical 

 change ; further, that boric acid ret.ards the development of 

 J\[ycodcnna, but does not prevent it in presence of already-formed 

 acetic acid. 



In Dingier' s Polylcch-yoiirnal 0. paper appears by Drs. Lunge 

 and Schappi, on bleaching-powdet. The results confirm the 

 now generally accepted formula first proposed by Odlinc, vi^., 

 CaOClCI. 



It w.is shown some time ago by II. T. Brown that alcoholic 

 ■fermentation proceeds more slowly under diminished than under 

 ordinary pressure. According to Bou?singaalt (Compt. rend.), 

 however, sugar is rapidly transformed into alcohol by the action 

 of yeast, if the carbon dioxide and alcohol, as these are produced, 

 be rapidly removed from the fermenting liquid. Addition of 

 alcohol soon stops fermentation under ordinary circumstances ; 

 Boussingault shows that if the ves-el containing the fermenting 

 liquid be connected with an air-pump which is worked energetic- 

 ally, fermentation proceeds rapidly even when a consider,i.ble 

 amount of alcohol has been added to the liquid. 



In connection with the recent liquefaction of ozone by Haute- 

 feuille and Chappuis, the following numbers, from a paper by 

 the same authors in Compt. rend., are of interest, as shoHing the 

 ■exact influence of temperature and pressui-e on the ozonising of 

 oxygen. Diminution of pressure does noi tend to increase the 

 amount of ozone produced, but decreased temperature exerts a 

 marked action in increasing the amount of oxygen transformed 

 into ozone ; — 



Tension of oione. 



Tension 

 of 



oxygen. -23" 0°. 20". 



760 io3'70 82'84 S3'96 



380 51-68 38-76 31-54 



30-60 22-20 



Proportion of ozone by weight 





22 30 



22-95 

 16-53 



A. DlTTE describes in Compt. rend, a number of new fluorine 

 compounds of uranium ; the most important are UF^ . 8HF and 

 UOjFj, produced by the action of hydrofluoric acid on the oxide 

 UjOg ; when the former compound is heated in a closed platinum 

 dish it melts, gives off hydrofluoric acid and small quantities of 

 the oxyfluoride UOF^, which compound is produced in larger 

 quantity by heating the above-mentioned o.xyfluoride, UOjF„, in 

 a closed vessel. The hexfluoride UF,., is produced by healing 

 the double salt UF^ . 8HF in an open crucible. Various double 

 salts are also described, the general formula b.ing UO„F„. 4MF, 

 ■where M may be K, Na, Li, Rb, or Tl. 



Cleve has made a redetermination of the atomic weight of 

 the very rare metal erbium (Compt. rend.). Assuming the 

 formula of the oxide to be Er.Oj, the atomic weight of the metal 

 is 166. Pure erbia, Er;03, is a beautiful rose-coloured earlli, 

 slowly soluble in acids, having a specific gravity of S-64, and 

 forming salts characterised by a deep-red colour; several of 

 these salts are described by Cleve. 



The same author has succeeded in separating nearly pure 

 thulium ; this metal and its salts are colourless, but solutions of 

 the salts show two absorption bands, one strongly marked in the 



red, and one bnad band in the blue. The atomic weight of 

 thulium is 129-6 or 170-7, according as the metal is regarded as 

 di- or tri-valent. 



PHYSICAL NOTES 

 It is stated that amongst the recent discoveries of Prof. Bell 

 in connection with the photophone research is the jinteresting 

 fact that melted sulphur conducts electrically like selenium, but 

 only at temperatures below that at which it thickens and becomes 

 dark and viscid. 



The Comptes rendus for November 2 informs us that Prof. 

 Graham Bell and M. Janssen have attempted to /lear with the 

 photophone the sounds believed to accompany the rapid com- 

 motions taking place in the solar photosphere. The experiments 

 were made at the Observatory of Meudon, a selenium cylinder 

 being placed in different parts of an image of the sun some two 

 feet in diameter. No very conclusive results were obtained, but 

 M. Janssen has further suggested that a sort of concentrated 

 effect might be obtained by passing a number of successive pho- 

 tographs of a sun-spot across a beam of light, the variations of 

 the intensity of the beam producing sounds when they fall upon 

 the sensitive "photophonic pile" of selenium. Some experi- 

 ments in furtherance of this suggestion are now proceeding. 



Having imdertaken a series of researches upon the rapidity 

 of evaporation of liquids, in dependence from the cohesion of 

 molecules on their surfaces, M. Sreznevsky has measured how 

 this rapidity varies w-ith the variations of the height of the 

 meniscus. He has established that, the diameter of the meniscus 

 remaining invariable, the rapidity of evaporation increases as 

 the height of the meniscus diminishes, that is, as its radius in- 

 creases. There is however an anomaly as to this last law for 

 distilled water : when the evaporation is measured in a meniscus 

 the height of which is greater than the radius of its basis, the 

 rapidity of evaporation increases throughout, however the radius 

 of the meniscus begins by diminishing, and increases only after 

 having passed through a minimum, but this minimum does not 

 have a corresponding minimum in the rapidity of evaporation. 



At the recent meeting of the Helvetic Society of Natural 

 Sciences M. Forel described a thermal bar which is developed 

 in winter parallel to the shore of a lake of fresh water, and which 

 separates the pelagic from the littoral region. The water of the 

 former region remains long, and in some lakes always, at a tem- 

 perature above 4" C. ; in the littoral region, if the winter be cold, 

 the temperature descends between 4° and zero ; and between 

 the two there is a band of water at 4°, descending to the bottom 

 — a kind of mountain with crest parallel to the shore and a talus 

 on either side. 



M. DuFOUR described at the same meeting an apparatus for 

 indicating the variations of chemical intensity of the sunlight. It 

 has some likeness to Draper's tithonometer ; the principle is, 

 opposing the variable action of light on a mixture of chlorine 

 and hydrogen, with an electric current (of variable intensity, and 

 measurable each instant), which by its passage causes decomposi- 

 tion of a quantity of hydrochloric acid equal to that produced 

 by action of the light on the mixture of chlorine and hydrogen. 

 The apparatus is like a Rumford differential thermometer ; in 

 one bulb is some hydrochloric acid solution, with carbon elec- 

 trodes, in the other some sulphuric acid. The light acts on the 

 former. One mode of measurement is to note the time taken in 

 displacement of the sulphuric acid column a certain distance 

 along the connecting tube. Then bring back the column to its 

 original position by passing the current. 



M. PiCTET has lately made experiments (Arch, de Sci.) 

 as to the dissolving power of gases and vapours on one 

 another. Various solutions of alcohol and water were suc- 

 cessively put into one of two glass balloons connected by 

 a tube ; pressure was diminished with an air-pump, so that 

 the space became filled with vapours from the mixture. By 

 closing the tapered point of the second balloon with the 

 blowpipe, the apparatus allowed of distillation being effected 

 with small differences of temperature. Plunging successively 

 the balloon that held the solution in water at from 0° to 80", 

 and the other in water only l" or a fraction of a degree below- 

 that of the liquid, M. Pictet got condensed products, the quality 

 of which indicated what "aflinity of solution" existed between 

 water and alcohol. The following conclusions were arrived at : 

 The weight of condensed liquid is proportional, in unit time, to 



