104 



CHEMISTRY. 



of water to each ; and within three minutes ob- 

 serve the shades of color. The number of drops 

 of tannin solution used in the tumbler which 

 corresponds in shade of color to the tumbler 

 containing the infusion of bark indicates the 

 percentage of tannin in the bark. 



A new process for making bleaching powder 

 and caustic soda has been patented by J. D. 

 IVunock and J. A. Bradburn. In it salt is 

 heated in a still by steam or its equivalent with 

 nitric acid ; the resulting gases, nitrosyl chloride 

 and chlorine, are passed through a small vessel 

 containing nitric acid and manganese dioxide, 

 the resultant chlorine being passed through a 

 washer and then to the bleaching-powder cham- 

 ber. The nitric acid in the sodium nitrate is 

 recovered by furnacing with oxide of iron, and 

 the mixture is lixiviated to recover caustic soda ; 

 the manganese nitrate is recovered by heat, and 

 the manganese dioxide is used over again. 



A new and very simple method of producing 

 indigo by synthesis is described by Dr. Flimm, 

 of Darmstadt. The principal step is the fusion 

 of the monobrornine derivative of acetanilide, 

 C 6 H.NH.CO.CH 2 Br, with a caustic alkali. The 

 indigo is separated by dissolving the product in 

 water and adding a little ammonia or ammoni- 

 um-chloride solution, or by dissolving the fused 

 mass in dilute hydrochloric acid and adding a 

 little ferric chloride. 



In his later experiments on fluorine, M. Mois- 

 san has prepared the gas in larger quantity and 

 a greater state of purity, and has determined 

 some of its physical properties. By its proper- 

 ties and its atomic weight it belongs at the head 

 of the chlorine family (F, Cl, Br, and I). When 

 looked at in considerable thickness and against 

 a white background, it appears of a greenish- 

 yellow color, fainter than that of chlorine at 

 the same depth, and more yellowish. A small 

 quantity of water introduced into the tube con- 

 taining fluorine is decomposed, with formation 

 of hydrofluoric acid and ozone. 



Phosphorus trifluoride has been obtained by 

 M. Moissan by heating a mixture of lead fluor- 

 ide and copper phosphide, and by the action of 

 arsenic trifluoride upon phosphorus trichloride ; 

 but gently warming a mixture of zinc fluoride 

 and phosphorus tribromide has been found a 

 more convenient process. The gas possesses a 

 very sharp odor, but does not fume in the air. 

 It is very slowly absorbed by water, but is de- 

 composed immediately by the solution of 

 chromic acid or of potassium permanganate. Its 

 density as determined by M. Moissan is 3-03, 

 while its calculated density is 3'08. When a 

 measured quantity of the gas is heated over 

 mercury in a closed glass vessel, it is decomposed 

 by the silica of the glass, and the volume is 

 diminished by one fourth, four molecules of 

 PF S becoming converted into three molecules of 

 gaseous silicon tetrafluoride, SiF 4 . 



In a paper on the spontaneously inflammable 

 liquid hydride of phosphorus, P 2 H 4 , Drs. Gatter- 

 mann and Haussknect, of Heidelberg, describe 

 an improved method of preparing the substance 

 from phosphide of calcium, by which it is ob- 

 tained almost perfectly pure, and add consider- 

 ably to knowledge of its properties. Liquid 

 P 9 H 4 boils spontaneously and without decom- 

 position when not suddenly heated, at 58 C., 



under a pressure of 753 mm. Its specific gravity 

 at 12 C. is 1-007. Exposed to sunlight it be- 

 comes yellow in half an hour, a result of the 

 formation of P 4 H 2 , which remains at first dis- 

 solved. After two or three hours of exposure, 

 the yellow solid begins to separate, and in about 

 a day and a half total decomposition takes 

 place, in accordance with the equation 5P 2 II 4 = 

 6PH S + P4H 2 . In consequence of this property 

 sealed tubes containing the substance exposed in 

 daylight are very dangerous articles. The ac- 

 cumulation of PH.3 makes them liable to explode 

 with a deafening concussion and the production 

 of a wide-spreading and very brilliant flame. 



A method of detection of adulteration in es- 

 sential oils by determinations of specific gravity 

 at 60 F., potash absorption, iodine absorption, 

 and boiling point, is described by Rowland Will- 

 iams, who has found it satisfacto'ry in the case of 

 some 60 specimens, representing 26 of the most 

 important essential oils occurring in commerce. 

 The importance of having a trustworthy test is 

 illustrated by the fact that one of the cheapest 

 of the essential oils citronelle is largely so- 

 phisticated with kerosene. "What, then, must 

 be the case with some of the more expensive oils, 

 the cost of which is enormous, when compared 

 with that of citronelle ? " 



It is suggested by Edward W. Morley that 

 hydrogen as prepared by all the ordinary pro- 

 cesses almost inevitably contains impurities, the 

 most important being carbon, which are liable to 

 affect determinations of its specific gravity and 

 atomic weight. If all impurities but nitrogen 

 are removed, the residual nitrogen can be deter- 

 mined, although with some manipulative diffi- 

 culty. The author has succeeded in obtaining 

 hydrogen in which there is no carbon, no sul- 

 phur, and, he believes, no oxygen, and in which 

 the quantity of remaining nitrogen is very minute. 



In M. Moissan's new method of preparing flu- 

 orine, fluoride of platinum is first obtained by 

 introducing a bundle of wires of the metal into a 

 thick platinum or fluor-spar tube, through which 

 a current of fluorine gas from the electrolysis 

 apparatus is passed. The wires are converted 

 to fluoride by heating to redness, and are then 

 quickly transferred to a dry stoppered bottle. 

 When the anhydrous fluoride is heated to bright 

 redness in a platinum tube closed at one end 

 fluorine is evolved as a gas. The residual plati- 

 num will consist of crystals of the metal. The 

 fluoride of platinum formed in the earlier part 

 of the process is exceedingly hygroscopic, and 

 with water forms hydrated platinic oxide and 

 free hydrofluoric acid. M. Moissan has also 

 prepared in the same manner a fluoride of gold, 

 which is likewise very hygroscopic and decom- 

 posable by water, and yields gaseous fluorine on 

 being heated to redness. 



A. A. Breneman gives the following method 

 of obtaining opaque soap bubbles for gas experi- 

 ment: Two flasks, arranged like gas-washing 

 bottles and tied together so as to be handled as 

 one, are filled to a measured depth with strong 

 NPIs and HN0 8 respectively. The long tube of 

 each bottle reaches nearly to the surface of the 

 liquid, but does not touch it ; the short tube 

 ends just below the respective stoppers. On 

 forcing any gas first through the long tube into 

 the bottle containing HN0 3 , and from that 



