August 29, 1878] 



NAT^URE 



473 



Ammonium.— T)x. Edward W. Davy, Professor of Forensic 

 Medicine, Royal College of Surgeons, Ireland, read, on behalf 

 of his colleague, Dr. Charles A. Cameron and himself, a paper 

 containing the results of some observations -which they had 

 conjointly made on the action of heat upon the selenate of 

 ammonium, from which they have shown that, when that salt 

 is exposed to heat, it first resolves itself into ammonia and an 

 acid selenate of ammonium (a hitherto undescribed salt), and that 

 this latter, on the application of a higher temperature, breaks 

 itself up into water, selenium, selenious anhydride, and nitrogen, 

 thus showing that in the first stage of the decomposition of this 

 selenate by heat it resembles the sulphate of ammonium in fur- 

 nishing an acid salt under the same circumstances, but that in 

 the separation of selenium in the second stage of the process there 

 is no analogy between the sulphate and selenate of ammonium. 



Abstract of a paper On the Action of Chlorine upon the 

 Nitroprtissides. — Dr. Edmund W. Davy read a paper On the 

 Action of Chlorine upon the Nitroprussides, an interesting class 

 of compounds obtained by the su:tion of nitric acid on the 

 soluble ferro- or ferri-cyanides, which were first investigated by 

 Dr. Lyon Playfair, several years ago. Dr. Davy has ascer- 

 tained that the statements which exist in the different standard 

 works on chemistry as to chlorine having no action on those 

 salts, is incorrect, at least as regards several of the nitroprussides 

 which he has made the subject of investigation, for he has found 

 that some of them are immediately, and others, after long ex- 

 posure, more or less, acted on by that substance, even when 

 they are excluded from the light. When, however, they are 

 subjected to the combined action of chlorine and the sun's rays, 

 they are soon completely decomposed, the principal products 

 being an oil-like matter, which agrees in its properties with the 

 substance known under the name of chlorocyanic oil, ferric 

 chloride, hydrochloric acid, and a chloride of the metallic base 

 of the salt employed. 



The following nitroprussides, viz. , those of potassium, sodium, 

 barium, calcium, zinc, iron, and silver, were found to be those 

 decomposed when exposed to the action of chlorine and sunlight ; 

 and it is probable that other nitropinissides would be similarly 

 affected. The only one of those salts, however, M'hich the 

 author has observed resisting this action is that of copper, which 

 has remained apparently unaffected after some weeks' exposiu'e 

 to its influence. 



On the Spectrum of Chlorochromic Anhydride, by Dr. John- 

 Stone Stoney and Prof. Reynolds. — The authors exhibited and 

 described the spectrum produced by the absorption of the 

 vapour of chltfrochromic anhydride. This spectrum is of pecu- 

 liar interest from its having supplied information as to the dura- 

 tion and character of the motion of the molecules of the gas 

 which produce it. The spectrum consists of lines nearly 

 equally spread, but of various intensities. From the posi- 

 tion of the lines, of which 105 have been examined, it has 

 been ascertained that they are all to be referred to one motion 

 in the molecules of the gas of which they are all harmonics or 

 quasi -harmonics, and which, on the supposition that they are 

 harmonics, is repeated 8io,ocxd,ooo,ooo every second in each 

 molecule, and from the succession of intensities it may be sur- 

 mised that this motion is in some way related to that of a par- 

 ticular point in a violin string vibrating under the influence of 

 the bow, viz., a point nearly, but not quite, two-fifths of the 

 string from the one end. 



Ott a New Method of Alkalimetry, by Dr. Louis Siebold, 

 F.C.S. — The plan recommended consisted in the reverse appli- 

 cation of Liebig's process for estimating hydrocyanic acid, and 

 was based on the fact that the volumetric determination of an 

 alkaline cyanide by means of silver nitrate was in no wise 

 affected by the presence of free hydrocyanic acid. From the 

 volume of silver solution used the quantity of alkali might be as 

 readily calculated as that of the cyanogen. If the applicability 

 of this process for alkalimetric purposes were confined to the 

 estimation of caustic alkalies nobody would, in Dr. Siebold's 

 opinion, think of using it in preference to the process commonly 

 adopted j but he wished to show that it might with great advan- 

 tage be applied to the determination of alkaline carbonates. 

 From '5 to one grain of the potassium or sodium carbonate 

 should be dissolved in about loo c.c. of distilled water, the solu- 

 tion mixed with an excess of hydrocyanic acid (10 to 20 c.c. of 

 acid of Scheele's strength), and then decinormal solution of 

 silver nitrate added from a burette until a permanent opalescence 

 is produced, the reaction occurring according to the following 

 equation : — 



K2CO3 -1- 2HCy + AgNOg = KAgCya + KNO3 + COg. 

 Whereas under ordinaiy circumstances hydrocyanic acid was 

 incapable of decomposing alkaline carbonates it effected a com- 

 plete decomposition in the presence of silver nitrate. The 

 mixture did not require boiling, and the whole operation might 

 be performed within a few minutes. If, after the end of the 

 titration, the mixture wei-e boiled, and the addition of deci- 

 normal solution of silver nitrate proceeded with, this time using 

 potassium chromate as an indicator, the volume of silver solution 

 required to insure complete precipitation of the silver cyanide 

 would be exactly equal to that used in the first titration. This 

 second reaction might then, if desired, be used as a check on the 

 determination. In the presence of chloride the volume of silver 

 solution used in the second experiment would be greater than 

 that used in the first, the difference between the two being 

 exactly that required to precipitate the chloride. In this manner 

 a determination of the chloride might be readily combined with 

 that of the alkaline carbonate. The following results were 

 quoted to show the accuracy of the process :— 

 Pure Potassium Carbonate. 

 Amount taken. Amount found. 



0-5850 0-5851 



0-1670 0-1672 



0-8775 o"S779 



In mixtures of pure potassium cai-bonate and sodium chloride- 

 Amount taken. Amount found. 



J K2CO3, 0-2000 -0-2005 



( NaCl, o-o68o 0-0683 



3 K2CO3, 0-9750 0-9750 



(NaCl, 0-1825 0-1830 



On the Estimation of Mineral Oil or Paraffin Wax 'when 

 mixed with other Oils or Fat. — William Thomson, F.R.S.E., 

 read a paper on this subject. He said that mixed oils were now 

 often used for lubricating purposes, and a common mixture, 

 composed of mineral oil with some animal, vegetable, or fish 

 oils, was now extensively used, and it was an important point to 

 be able by analysis to determine the amount of mineral oil 

 which such mixtures contained, and as he could find no pub- 

 lished process to effect this, he devised, after much work, the 

 following, which he found by repeated tests to give very accu- 

 rate residts : — He boiled some of the sample with an alcoholic 

 solution of caustic soda, which converted all the animal, vege- 

 table, or fish oils into soap. This was then mixed with sand, 

 evaporated to dryness on the steam bath, the residue placed in a 

 bottle washed with petroleum spirit, and distilled at a temperar 

 ture under 190° F. This dissolves out the mineral oil, leaving 

 the soap insoluble. The spirit is now distilled off fi-om the 

 spirit solution of mineral oil in a large flask, and after thus eva- 

 porating off the bulk of the spirit, the concentrated solution is 

 transferred to a smaller flask with a hole blown in its side, into 

 which is fitted a cork carrying a thermometer |and glass tube j 

 the thermometer should touch the liquid, going nearly to the 

 bottom of the flask. It is placed on a sand bath and heated at 

 a temperature not exceeding 220° F., and dry air blown into the 

 flask through the tube in the cork, to remove the last trace of 

 spirit, and the residue of mineral oil weighed and calculated on 

 the weight of the original mixed oil taken. 



On some Double Salts of Glucinum, by Prof. Emerson Rejmolds.^ 

 — This communication contained an account of some investiga- 

 tions upon some compounds of the rare metal glucinum, and 

 demonstrated by several interesting experiments how the author 

 had succeeded in obtaining the metal in a state of purity by the 

 use of the double fluoride of glucinum and potassium. A second 

 salt, double chloride of platinum, and glucinum, had also been 

 prepared in an exceedingly pure crystalline form. Dr. Reynolds 

 stated that he had also made experiments with a view to deter- 

 mine the specific heat of glucinum, which he fixed at '642, and 

 this multiplied by the probable atomic weight of the nietal^ 

 namely, 9*2 — gave 5-90, a result fairly in accordance with the 

 law of Dulong and Pettit. 



Summary of Investigations in the Pyridine Series, by Dr. W. 

 Ramsay. — These bases, which possess the general formula, 

 C„H2„— 5N, are tertiary bases. They form an additive product 

 with iodides of alcohol radicles, of which a good example is 

 C5H5N, CH3I, best named pyridine methyl-iodide, as it re 

 sembles a salt in its constitution. They are not attacked by 

 nitrous acid, and the cyanate, when heated, undergoes no mole- 

 cular change, but merely splits up into the base, and the usual 

 polymer of cyanic acid, cyanuric acid. 



