252 



NATURE 



[May 29, 19 19 



May 16) on the use of alcohol for the rapid drying 

 of gelatine negatives and prints. He gives curves that 

 show the drying action of alcohol under various condi- 

 tions, but perhaps the most interesting result is the 

 cause of the white deposit that so often appears when 

 this method is used. It is due to bicarbonate of lime 

 deposited because of its insolubility in alcohol. By 

 immersing the negative in very weak hydrochloric 

 acid (10 c.C of commercial acid to a litre of water) 

 immediately before putting it into the alcohol, the 

 deposition is avoided. This weak acid will remove a 

 deposit that has been allowed to form, and if the 

 patch is of small area it may be made to disappear 

 by breathing on it for a short time, because of the 

 moisture" and carbon dioxide in the expired air. Of 

 course, the use of soft water obviates this annoy- 

 ance, but the use of pure alcohol instead of "de- 

 natured" spirit does not, though this has often been 

 prescribed as a remedy. 



More than sixty years ago Pasteur showed that 

 glycerol was formed during the alcoholic fermentation 

 of sugar. The quantity found was about 36 per cent, 

 of the sugar fermented. Later, Laborde showed that 

 the quantity of glycerine produced varied according 

 to the kind of yeast used and its amount, more than 

 double the foregoing proportion being obtained in 

 some cases. Even so, this is a very small yield if 

 fermentation is regarded as a source of glycerol. It 

 is understood, however, that during the late war our 

 opponents supplemented their production by fermenta- 

 tion methods when fats, the ordinary source, ran 

 short. In Helvetica Chimica Acta (vol. ii.. No. 2) 

 K. Schweizer indicates the method used. It is known 

 that glyceric aldehyde and dihydroxyacetone can be 

 converted into glycerol by means of reducing agents, 

 and there is some evidence that one or both of these 

 substances may be produced as intermediate com- 

 pounds during fermentation. The working hypothesis, 

 therefore, was that these compounds, in the nascent 

 state, would be acted upon by a reducing agent and 

 converted into glycerol to a greater extent than in 

 ordinary fermentation. This was found to be the 

 case. On adding sodium sulphite, and working with 

 a neutral liquid, a yield of more than 21 per cent, of 

 glycerol was obtained. 



MoNOMETHYLAMiNE being a synthetic reagent of con- 

 siderable importance, a new method for its prepara- 

 tion will probably be of interest to organic chemists. 

 The reduction of chloropicrin yields different products 

 according to the reducing agent employed. Raschig 

 showed that when chloropicrin is reduced with 

 stannous chloride and hydrochloric acid, cyanogen 

 chloride is produced. If, however, iron-filings and 

 acetic acid (Geisse) or tin and hydrochloric acid 

 (Wallach) are used, monomethylamine is the major 

 product. Prof. P. F. Frankland and Messrs. F. 

 Challenger and N. A. Nicholls have studied the condi- 

 tions of the reaction (Journal of the Chemical Society, 

 February, p. i^q) and recommend the following pro- 

 cedure : — Iron-filings (500 grams) are gradually shaken 

 into water (2500 c.c.) containing hydrochloric acid 

 (60 c.c), and contained in a large earthenware jar 

 which is fitted with a stirrer and placed in a little 

 cold water. The chloropicrin (250 grams) is then 

 graduallv added, with very efficient stirring. The tem- 

 perature rises, and should be maintained at about 

 50° C. The smell of chloropicrin disappears after 

 three hours, and the mixture is then gradually added 

 to a boiling solution of sodium hydroxide into which 

 steam is blown. The methylamine is absorbed in 

 hydrochloric acid, the solution evaporated, and the 

 residue dried to constant weight. In this way a yield 

 of 95-5 per cent, of the amine hydrochloride contain- 

 ing only 35 per cent, of ammonium chloride is ob- 



NO. 2587, VOL. 103] 



tained. When reduced with a hot alkaline solution of 

 ferrous sulphate, chloropicrin gives a considerable 

 amount of ammonia. The method described for the 

 preparation of methylamine should prove valuable now 

 that large quantities of chloropicrin are r<-;idil\ pro- 

 curable. 



A NEW weekly journal devoted to industrial and 

 engineering chemistry, and entitled the Chemical 

 Age, is announced for publication on June 21 by 

 .Messrs. lienn Bros., Ltd., Bouvorie Street, E.C.4. 



OUR ASTRONOMICAL COLUMN. 



The Solar Eclipse. — The total eclipse of the sun 

 that will happen to-day is remarkable for the small 

 amount of attention that is ix ing given to observa- 

 tions of the corona and the sun's surroundings that 

 have formed the main object for which eclipse ex- 

 peditions have been organised during the last half- 

 century, but in place of these the opportunity is being 

 used to make investigations in several modern 

 branches of science. The Committee of the British 

 Association for Radio-telegraphic Investigation has 

 arranged a programme for sending and receiving 

 signals to determine their strength during the eclipse. 

 The Department of Terrestrial Magnetism of the 

 Carnegie Institution of Washington has arranged 

 observing parties at stations in America and West 

 Africa, who, in co-operation with various observatories 

 and individuals, will make special magnetic and allied 

 observations inside and outside the shadow belt. As 

 has already been announced, the British expeditions 

 to Brazil and West Africa will photograph the field 

 of stars around the sun for the purpose of detecting 

 any displacement due either to gravitation according 

 to the relativitv theory published by Einstein in 1915, 

 or to the effect of the sun's gravitation on the mass 

 that light is believed to have according to the electro- 

 magnetic theory. 



June METEORS.^Though twilight is strong in the 

 midsummer month, meteors are fairly numerous, and 

 probably more so than in April and May. Fireballs 

 are often seen, and particularly from a radiant point 

 in Scorpio. There is a possible cometary radiant on 

 Tune 10 from 273x0, and three others during 

 the last week of the month from 313x60, 

 13x6, and 213x53. The last appears to be probably 

 connected with the comet of Pons-Winnecke, which 

 afforded an unusually rich shower on June 28, 19 16. 

 Though no return of this display can be con- 

 fidently expected until 192 1 or 1922, it should be 

 looked for every year, as it may form an annual ex- 

 hibition, though really abundant at intervals of about 

 every six years. The great shower of Perseids begins 

 early in July, and there is strong evidence that the 

 same system furnishes an occasional meteor at the end 

 of June. Observers should therefore watch especially 

 for such an object during the moonless nights at the 

 end of June this year. 



Paris Observatory Reports. — ^The reports of the 

 French National Observatory have been made and 

 presented to the council annually during the war, and 

 those for the years 1916-18 have lately been received. 

 The work has naturally been much curtailed owing 

 to the absence of many of the staff on military service, 

 and a projected modification of the programme with 

 the principal meridian instrument has had to be held 

 in abevance. Also, it was considered prudent to take 

 precautions against damage to this and other instru- 

 ments, so that the reports show little in the way of 

 observation, the energies of such observers as were 

 available being devoted entirely to the requirements 

 of the time service, the errors of the clocks being 



