218 



CHEMISTRY. 



num points, that the platinum shall not be 

 moistened by the liquid. The separated carbon 

 is collected on an asbestos filter, dried in a cur- 

 rent of air, and burned with oxide of copper 

 and oxygen, in the usual manner. In this way 

 its weight is to be determined; while the quan- 

 tity of the iron dissolved is nearly enough found 

 by weighing the portion remaining after com- 

 plete solution of that which dips in the acid, and 

 subtracting from the entire previous weight 

 the sum of weights of this residue and of the 

 carbon. A piece of cast iron weighing about 

 124 grains dissolves in this way in 24 hours. 



Nitrogen in Iron. Eecent experiments have 

 determined not only that nitrogen is a constit- 

 uent of cast and wrought iron and of steel, but 

 further, that in these bodies it is present in 

 two conditions. That existing in one of the 

 two states is liberated in form of ammonia 

 when the iron is dissolved in hydrochloric acid, 

 the nitrogen uniting with nascent hydrogen. 

 The nitrogen present in the second state is left 

 in the carbonaceous mass which remains after 

 the iron is so dissolved, or which is obtained 

 by heating with sulphide of mercury. These 

 two states have been determined by the re- 

 searches of Ullgren, who concludes that the 

 quantities of nitrogen in both of them must be 

 ascertained by liberating the element in the 

 gaseous form. A consequence of the fact that 

 one portion of the nitrogen may remain mask- 

 ed as it were in the residue of solution, while 

 another readily manifests itself, must be that 

 the amount of the element in the sorts of iron 

 has been in some cases underestimated. The 

 entire paper is found in Liebig's "Annalen," 

 Oct. '62, and a note embracing the processes to 

 be employed, in the "Philos. Mag.," Dec. '62, 

 Supplement. 



New Fusible Alloy. Dr. B. Wood describes 

 ("Amer. Jour, of Science," March, 1862) a 

 new alloy produced by him, of cadmium 1 part, 

 lead 6, bismuth 7, which melts at 180 F., or 

 about midway between the melting points of 

 the old fusible metal (of tin, lead, and bismuth), 

 and of another fusible alloy described by him 

 in the same journal, 1860, (of cadmium, tin, 

 lead, and bismuth). The new alloy has a bril- 

 liant lustre and does not readily tarnish ; color, 

 bluish gray ; it is very flexible, and has about 

 the hardness of bismuth or of the common 

 "coarse solder." 



Cupreous Acetylene. M. Crova finds that 

 this substance, which is explosive, is produced 

 in copper pipes that have been long in use 

 for conveying coal gas. It is known that such 

 pipes, on being cleaned out, frequently give rise 

 to dangerous explosions ; and also that cupre- 

 ous acetylene detonates at high temperatures, 

 or on being struck. Crova placed a quantity 

 of reduced metallic copper in a flask containing 

 equal volumes of air and acetylene, and with 

 the addition in one instance of a little ammo- 

 nia. The copper became black, and the flask 

 being after some time opened under water, it 

 was found that the gases present had been 



absorbed slightly more when ammonia was 

 present. The copper being washed and dried, 

 and treated with hydrochloric acid, a consider- 

 able quantity of acetylene was disengaged. A 

 portion of the compound unacted on being 

 thrown on a heated metallic plate, explosion 

 resulted, and more violent than with the ordi- 

 nary cupreous acetylene. As coal gases al- 

 ways contain acetylene, and traces of air and 

 ammonia, the formation of this dangerous com- 

 pound in copper or bronze tubes conveying 

 such gases, must almost of necessity follow.. 

 (Comptes Rendus, September 8, 1862.) In Jan- 

 uary, 1863, a lady in Rochester, N. Y., was 

 knocked down by an explosion following in- 

 stantly upon the ignition of the gas in a room, 

 and which she was lighting in the usual man- 

 ner with a match. A boy near her was also 

 prostrated, and the lathing and plastering of 

 two or three rooms were torn off. The lady 

 has since suffered from a partial paralysis. The 

 explosive material was probably that just con- 

 sidered, or some other incidentally forming in 

 the pipes or fixtures delivering the gas. 



Improved Matches. Messrs. Letchford and 

 Company, London, improve the ordinary match- 

 es by substituting for the sulphur coating one of 

 melted paraffine, which impregnates the wood 

 and renders it more inflammable ; the ordinary 

 phosphorus coating, for ready ignition, is ap- 

 plied over this in the usual manner. These 

 matches remain uninjured by damp, being the 

 only sort found capable of igniting after six 

 hours' exposure to a moist atmosphere ; so that 

 they are particularly suitable for export. Other 

 advantages are their being free from the sul- 

 phurous acid fumes, on ignition, which are dis- 

 agreeable and sometimes hurtful to the lungs ; 

 and that, for the like reason, they do not when 

 lighted tarnish silver and other bright metallic 

 surfaces near to them. 



India Rubber Varnish. Dr. Bolley obtains 

 this varnish free from the usual imperfections; 

 that is, in a perfectly dissolved, fluid, and color- 

 less condition, by digesting India rubber cut 

 into small pieces for many days in benzine, fre- 

 quently shaking the containing bottle, then fil- 

 tering, allowing the liquid to rest, and again 

 straining through a woollen cloth. The resi- 

 due separated by this last process affords a good 

 water-proof composition. The varnish itself 

 incorporates easily with fixed or volatile oils, 

 dries fast, and if unmixed with any resin, does 

 not shine. It is extremely flexible, can be 

 spread very thin, and is unaltered by air or 

 light. Its great advantages as a varnish for 

 maps, prints, &c., are that it does not affect the 

 whiteness of the paper, nor crack and come off 

 in scales, nor produce a glare of reflected light 

 in the manner of resinous varnishes, and so 

 does not prevent the figure or print from being 

 seen equally well in all directions. Unsized pa- 

 per varnished with it can be written on with ink. 



Basis of Artificial Teeth. A composition to 

 form the basis of artificial teeth has been pro- 

 posed by M. and A. Gabrielj London. It con- 



