400 



NATURE 



[August 24, 189^ 



hhherto supposed, these experiments also show that nerve may 

 act on muscle without producing actual contraction, but only 

 some simple molecular vibration. 



We have received a catalogue of the library of the Akademie 

 der Naturforscher, prepared by Dr. Oscar Grulich. 



The City and Guilds of London Institute for the advance- 

 ment of technical education has issued its programme of the 

 technological examinations for the session 1893-94. 



" Symoxs's British Rainfall" for 1892 has been pub- 

 lished. It contains, in addition to the rainfall statistics 

 gathered from more than three thousand observers in Great 

 Britain and Ireland, several articles upon various branches of 

 rainfall work. 



A LECTURE on " Cholera Prospects and Prevention," recently 

 delivered by Dr. Thorne Thorne, F. R. S., to the technical 

 teachers of the National Health Society, has just been published 

 by the Society. The teachers and the Society must benefit by 

 putting themselves under such an excellent adviser as Dr. Thorne 

 is upon hygienic matters. 



The autumn session of popular science lectures at the Royal 

 Victoria Hall, Waterloo Bridge-road, will open on Tuesday, 

 September 5, with a lecture on " What I saw of New Zealand 

 and the noble Maori," by Capt. Chas. Reade, R.N. The three 

 other lectures of the month will be given by Prof. Maiden, and 

 will be as follows: — September;i2, "Picturesque Ireland ; " 

 September 19, "Australia";" September 26, "The World's 

 Fair and Chicago." 



Three more volumes of the comprehensive Aide-Memoire 

 series, published by Gauthier-Villars and by Masson have been 

 received. One, by M. Laurent Naudin, is on the manufacture 

 of varnishes. It is divided into two parts, dealing respectively 

 with the physical and chemical properties of the materials used, 

 and with the actual processes involved, in varnish manufacture. 

 M. G. Laverque is the author of a volume on turbines, which 

 is also divided into theoretical and practical parts. The third 

 volume is by M. A. Hebert, and deals with the means of detect- 

 ing the adulteration of alcoholic drinks. 



The Journal of the Marine Biological Association (vol. iii., 

 No. l) contains lists of the Nemertines of Plymouth Sound, by 

 Mr. T. H. Riches, and the Turbellaria of Plymouth Sound and 

 the neighbourhood, by Mr. F. W. Gamble. Dr. Benham contri- 

 butes a paper on the post-larval stage of Arenicola marina, and 

 Mr. E. W. L. Holt continues his description of the North Sea 

 investigations carried on by him at the Marine Fisheries 

 Society's laboratory at Cleethorpes. Mr. J. T. Cunningham 

 contributes two interesting articles on the immature fish ques- 

 tion, and the coloration of the skins of flat fishes. 



The United States National Museum has issued in separ- 

 ate form the report of Dr. J. P. McMurrich on the Actinia; col- 

 lected by the U.S. Fish Commission steamer. Albatross, during 

 the winter of 1887-88. The reports deals with the Edwardsiae, 

 Protaclinias, Hexactiniee, and Ceriantheoe. Dr. McMurrich 

 will give the results of his studies of the Zoanthese in a future 

 report. Other recently-received excerpts from the Proceedings 

 of the U.S. National Museum include a "Description of some 

 Fossil Plants from the Great Falls Coal Field of Montana," 

 by Mr. W. M. Fontaine, and a paper "On the Occurrence of 

 the Spiny Boxfish (Genus Chilomycterus) on the Coast of 

 California," by Prof. Carl H. Eigenmann. 



An improved mode of preparing the ammonium salt of per- 

 sulphuric acid, NH4SOJ or (NHi)^ ^fin, is described by Dr. 

 Elbs, of Freiburg, in the latest number of the Journal fur 

 Praktische Chemie. The potassium, ammonium and barium 



NO. 1243, VOL 48] 



salts of persulphuric acid were obtained two years ago by Dr. 

 Marshall, of Edinburgh, in large well-developed crystals as 

 described in our note of Vol. 44, p. 577, and since the publi- 

 cation of Dr. Marshall's memoir M. Berthelot, who first pointed 

 out the existence of the acid and its anhydride, has published 

 an account of his further experiments upon the subject, fully 

 confirming the results obtained by Dr. Marshall, and adding 

 further details. M. Berthelot's latest form of electrolytical 

 apparatus for the preparation of the persulphates by the electro- 

 lysis of solutions of the ordinary sulphates in sulphuric acid 

 consisted of a double cell, the inner portion being constructed 

 of porous porcelain. Into this inner porous cell of about 150 

 c.c. capacity was placed a concentrated solution of ammonium 

 or potassium sulphate in dilute sulphuric acid, while the outer 

 cell was filled with more of the dilute acid. M. Berthelot ap- 

 pears to have considered it essential to employ an anode of small 

 surface in the inner cell, a piece of stout platinum wire being 

 preferred ; but a kathode of large surface was considered requisite 

 in order to diminish the resistance of the arrangement, and a 

 large plate of platinum was employed for this purpose. A 

 current of three amperes was allowed to pass through the appa- 

 ratus for fifteen to twenty hours, when a yield of about fori y to 

 forty-five grams of ammonium persulphate, corresponding to a 

 yield of sixteen per cent, of the theoretically possible, was ob- 

 tained. With the improved form of apparatus and under the 

 conditions described by Dr. Elbs, it is possible to obtain an 

 average yield of sixty-five /fr«K/. of ammonium persulphate, 

 the amount having even reached eighty-five /^/- ««/. in one 

 experiment. As anode or positive pole a spiral of platinum 

 wire is employed, and as kathode or negative pole a piece of 

 sheet lead bent into a cylindrical form and surrounding the 

 inner porous cell. The outer liquid consists of equal portions 

 by volume of water and oil of vitriol, and the inner liquid is a 

 saturated solution of ammonium sulphate in sulphuric acid 

 diluted with eight times its volume of water. The apparatus 

 is cooled during the passage of the current by a bath of poutded 

 ice. If cold spring water is available, however, the cooling 

 may conveniently be effected by substituting for the leaden 

 C) Under in the outer vessel a worm of leaden tubing, through 

 which the cold water is driven. The current of two to three 

 amperes is only permitted to traverse the apparatus for three or 

 iour hours, when the contents of the inner cell are filtered 

 through glass wool, which letains in the funnel the crystals of 

 ammonium persulphate produced. The crystals are drained on 

 porous plates, and the filtrate is again saturated with sulphate 

 of ammonia, returned to the inner cell, and again electrolysed. 

 There is no advantage in prolonging the experiment to twenty 

 hours, inasmuch as the formation of persulphate occurs much 

 more slowly after a time. After the first experiment, when a 

 considerable quantity of ammonium peisulphate remains in 

 solution, one hundred parts of water at the ordinary temperature 

 dissolving sixty-five parts of the salt, about forty grams of crys- 

 tals are obtained in each operation of three to four hours. In 

 order to recover the persulphate remaining dissolved after the 

 conclusion of ihe preparations it is convenient; to precipitate it 

 as the potassium salt by the addition of a solution of carbonate 

 or acetate of potassium. Potassium persulphate is much less 

 soluble than the ammonium salt, one hundred parts of water, under 

 the same circumstances as mentioned in the case of the latter 

 salt, only dissolving two parts of the potassium salt. It would 

 thus appear to be most advantageous to prepare the soluble ammo- 

 nium salt as the starling-point for a study of the persulphates, and 

 the method described by Dr. Elbs renders the operation both 

 simple and cheap, and affords it in comparatively large quan- 

 tities in a short period of time. The product may be purified 

 from traces of admixed ordinary sulphate by first recrystallising 

 a small portion, and subsequently washing the main quantity 



