108 



CHEMISTRY. 



quantitative reaction, by means of which any 

 desired substitution of chlorine may be readily 

 effected in a large number of hydrocarbons. 

 It consists of heating in a sealed tube the cal- 

 culated quantities of hydrocarbon and phos- 

 phorus pentachloride, when the pentachloride 

 is dissociated into the trichloride and free 

 chlorine. The value of this means of substi- 

 tution lies in the fact that, instead of the un- 

 certain results so frequently obtained by the 

 graduated use of free chlorine, it now becomes 

 possible to obtain a quantitative yield, in a form 

 that is easily separable, of the particular chlo- 

 rine derivative desired. 



R. T. Thomson publishes two methods for the 

 estimation of aluminum in the presence of a 

 large proportion of iron. One is for use when 

 but little, the other when a larger proportion 

 of manganese is present. Both depend upon 

 the reduction of the iron to a ferrous state and 

 the precipitation of aluminum as a phosphate 

 by means of ammonia and ammonium acetate. 



Franke describes the preparation of man- 

 ganic anhydride, MnO 3 . To obtain it, dry po- 

 tassium permanganate is added to well-cooled 

 sulphuric acid ; the green solution formed is 

 either heated to 50 C., after addition of a lit- 

 tle water, or better, allowed to flow, drop by 

 drop, on to calcined soda. Violet vapors ot 

 manganic anhydride are evolved, and condense 

 in the receiver to a dark amorphous mass. 

 "When heated at 50 it volatilizes in violet va- 

 pors, with partial decomposition into manganic 

 dioxide and oxygen. If heated more strongly, 

 it is completely decomposed into those sub- 

 stances. It dissolves only sparingly in water, 

 imparting to it a deep-red color. It is also a 

 most vigorous oxydizing agent. 



Industrial Chemistry. Mr. A. E. Fletcher, chief 

 inspector under the Alkali Works Regulation 

 Act, describing in the British Association the 

 present position of the alkali manufacture, said 

 that Leblanc's process had withstood the at- 

 tacks of all rivals, and that, although the com- 

 petition against it was fiercer than at any pre- 

 vious period, he thought that it would main- 

 tain its position for many a year to come. 

 During the last ten years slight alterations had 

 been proposed in the proportions to be used of 

 the three ingredients forming the charge of the 

 black-ash furnace the coal, brimstone or 

 chalk, and sulphate of soda and in the method 

 of throwing them in the furnace. The main 

 process, however, of fusing these materials to- 

 gether, and, when cold, lixiviating the mixture 

 for the extraction of carbonate of soda, is fol- 

 lowed almost exactly as was proposed by Le- 

 blanc, now almost a century ago. It must be 

 acknowledged that this process is seriously at- 

 tacked by another, so far as the manufacture 

 of carbonate of soda is concerned, and it would 

 have been by this time completely driven out 

 of the market by its rival, but for the impor- 

 tance of its by-product. Bleaching-powder had 

 not as yet been made in connection with the 

 ammonia process. Three methods were, how- 



ever, proposed, and were on their trial for the 

 attainment of that end. If bleaching-powder 

 could be produced by either of them at a mod- 

 erate cost, the older alkali process could no 

 longer stand its ground. 



Traube has made some new researches on 

 the part taken by water in the combustion of 

 carbonic oxide, which have a double interest 

 in their bearing on the properties of water- 

 gas, and of the peroxide of hydrogen. The 

 peroxide of hydrogen is constantly finding in- 

 creasing application, more or less diluted with 

 water, as an oxidizing, bleaching, and disin- 

 fecting agent. It is used for the bleaching of 

 bones and ivory, wool, silk, feathers, and hair; 

 in housekeeping for removing wine and fruit 

 spots from white cloths. It stops all kinds of 

 fermentation, and is therefore a good preserv- 

 ing agent. Destroying all micro-organisms, it 

 is valuable in the treatment of wounds and skin- 

 diseases. To prevent decomposition, however, 

 the solutions of this substance must be kept at 

 a low temperature and protected from the 

 light. According to Dixon's experiments, a 

 perfectly dry mixture of oxygen and carbonic 

 oxide can not be exploded by any ordinary 

 means; and ignition will not take place until a 

 certain quantity of the vapor of water is intro- 

 duced. Traube has confirmed these imj ^*- 

 tant observations, and has found, further, t . " 

 carbonic oxide already inflamed is immediately 

 extinguished in a perfectly dry atmosphere. 

 He found, further, that carbonic oxide, even at 

 a high temperature, will not decompose water, 

 so that no trace of carbonic acid or hydrogen is 

 developed under those conditions. But hydro- 

 gen has a reducing action on carbonic acid at a 

 red heat ; and if we pass an electric spark 

 through a mixture of the two substances, car- 

 bonic oxide and water are formed. Traube, 

 therefore, concluded that water plays a simi- 

 lar part in the combustion of carbonic oxide 

 at a red heat to that which it plays, according 

 to his researches, in the slow combustion of 

 the baser metals; that is, that in both cases it 

 is decomposed with the formation of peroxide 

 of hydrogen. Carbonic oxide, which alone 

 can not decompose water, exerts this action 

 with the aid of oxygen. In fact, direct experi- 

 ments show that the flame of carbonic oxide 

 when brought in contact with water gives off 

 so much peroxide of hydrogen that very intense 

 reactions are produced with potash permanga- 

 nate or zinc iodide, and sulphate of iron, or 

 with chromic acid and ether. 



Cholesterin is a fat which occurs in the 

 feathers of birds and other animal coverings, 

 and is present in considerable proportions in 

 wool. Because of its uncleanness and unpleas- 

 ant smell, and of its containing 25 per cent, of 

 free fatty acid, it has to be removed in the prep- 

 aration of the fabric; while hitherto it has 

 been regarded as of no value except as a com- 

 bustible or as the raw material for illuminating 

 gas. The clear fat arising from the combina- 

 tion of cholesterin with the fatty acids has 



