CHEMISTRY. (ATOMIC WEIGHTS.) 



107 



part an exceedingly brilliant flame appears, 

 which is due to the reaction of magnesium with 

 water vapor. The magnesia thus ionned is left 

 in long filaments. Another interesting experiment 

 is upon the reaction of aluminum on alumina. 

 Four atoms of the metal to one molecule of the 

 oxid are mixed; upon igniting they react with 

 vivid incandescence, forming, it is represented, the 

 oxid ALO. 



It is shown- by W. H. Stanger and B. Blount 

 that in preparing cement by the rotary process it 

 is possible to approach the theoretical ratio of 

 acids to bases, arid to obtain a stronger and 

 sounder cement than the best cements commer- 

 cially prepared by the discontinuous process. The 

 raw materials at the works with which the au- 

 thors are concerned are a calcareous shale and 

 a limestone. These are crushed, dried, finely 

 powdered, and fed mechanically into rotary kilns. 

 The fuel is powdered coal driven in by a 

 blast of air through an injector burner at the 

 lower end of the kiln. An intensely hot flame, 

 readily controllable, is thus produced, and heats 

 the raw materials introduced at the upper end of 

 the kiln, which are caused to travel downward 

 in a direction opposite to that of the blast. The 

 materials are then heated systematically, and at 

 the lower end of the kiln near the burner become 

 converted into clinker. This falls into a rotating 

 cylinder lined \vith fire-brick, through which is 

 passing a current of air serving to feed the coal- 

 dust flame. A great part of the heat of the 

 clinker is thus regenerated. The clinker is then 

 roughly crushed between rollers that work under 

 a spray of water, and passes through a final ro- 

 tary cooler into trucks by which it is conveyed 

 to stock boxes over the grinding plant. Thus, 

 from the crushing of the raw materials to the stor- 

 ing of the finished cement, no hand labor is em- 

 ployed, all conveyance, distribution, and transmis- 

 sion being done mechanically. 



In a method for the preparation of amids from 

 the corresponding aldehydes described by Messrs. 

 Pickard and Carter, the aldehyde dissolved or sus- 

 pended in water is shaken with a slight excess of 

 ammonia persulfate and a certain quantity of 

 lime; after the reaction is over no difficulty is 

 met in separating the amid in quantities amount- 

 ing to 30 or 40 per cent, of the aldehyde taken. 

 The metho*d is said to lend itself to the prepara- 

 tion of alkyl-substituted amids; when it is used 

 for this purpose, potassium sulfid is substituted 

 for the ammonium salt, and the alkylamin is 

 present. 



In a new method of preparing anilin and its 

 analogues, by MM. Paul Sabbatier and J. B. Sen- 

 derens, a mixture of hydrogen and nitrobenzene 

 vapor is passed over reduced copper kept at a 

 temperature of from 300 to 400 C., when the 

 yield of anilin is nearly theoretical. If nickel is 

 employed instead of copper, the reaction goes far- 

 ther, even at 200, benzene and ammonia being 

 produced. 



Atomic Weights. In a lecture at the Royal 

 Institution, May 30, dealing with the combina- 

 tions of carbon, Prof. Dewar exhibited some ex- 

 amples of exothermic carbon compounds, which 

 on decomposition give out heat, and remarked 

 that such bodies, being characterized by the fa- 

 cility with which they passed into new combina- t 

 tions, w r ere especially important as a basis for 

 organic synthesis. An infinite number of carbon 

 compounds were already known, and in addition 

 to those which occurred in the animal and vege- 

 table worlds, chemists w r ere every year preparing 

 thousands of absolutely new ones which had never 

 existed before. Why had carbon this power of 



unlimited multiplication of new bodies a power 

 in which it differed so markedly from other ele- 

 ments? Silicon most nearly resembled it, and was 

 much more abundant in the world, yd in spito 

 of attempts to constitute a chemistry ol silicon 

 like that of carbon, chemists were very t;n from 

 getting the former to make compounds in the 

 same way as the latter. In attempting un ex- 

 planation they entered a region of speculation, 

 but there was a basis to go upon in the indispu- 

 table fact that the smallest chemical unit of car- 

 bon combined with four units not more of hy- 

 drogen. Kekule, in whose hands and those of 

 Frankland this fact had resulted in the forma- 

 tion of the doctrine of atomicity, threw out the 

 brilliant idea that carbon was capable of un- 

 limited combination with itself, as an explana- 

 tion of the multiplicity of its compounds, and con- 

 ceived of the carbon atoms as linking themselves 

 together in a chain. In this way something was 

 lost of the combining power of each atom for 

 example, while two separate atoms would have 

 altogether eight combining powers, when linked 

 together the combined couple could have only 

 six but the number of possible compounds was 

 indefinitely increased. 



The question of a possible variability in the 

 valency of carbon is involved in certain experi- 

 ments described by Herr M. Gomberg. By the 

 action of such metals as silver, zinc, and mercury 

 upon triphenyl chlormethane, (C H 3 ) 8 Ccl, the 

 halogen was removed, and, working in the com- 

 plete absence of air, the resulting product was 

 not, as would be expected, hexaphenylcthane, but 

 an unsaturated body w r hich. readily absorbed oxy- 

 gen from the air and combined directly with the 

 halogens. The author thinks that the only pos- 

 sible explanation of the observed facts lies in the 

 assumption that the substance is really triphenyl 

 methyl, (C H 5 ) 3 C, in which the carbon is triva- 

 lent. 



The values obtained for the atomic weights of 

 iodin and tellurium having been inconsistent 

 with their relative positions in Mendeleef's table, 

 numerous determinations of the atomic weight of 

 tellurium have been made in recent years, the re- 

 sults of which have varied from 127.5 to 128; but 

 all above that of iodin instead of being below it, 

 as required by the periodic law. It was pointed 

 out by O. Steiner that these determinations had 

 been made from the analysis of inorganic prepara- 

 tions, the absolute purity of which from sub- 

 stances of different atomic weights from that of 

 tellurium had not been demonstrated. Taking 

 the diphenyl telluride, Te(C c H 3 ) 2 , a stable and 

 well-defined compound, and distilling without de- 

 composition in a vacuum,, this author obtained 

 12G.4 as the approximate atomic weight of tellu- 

 rium a figure much lower than the other de- 

 terminations, and corresponding with the predic- 

 tion of the periodic table. The investigation is 

 not yet complete. 



The principle that the transparency of sub- 

 stances to the Rontgen rays depends upon the 

 atomic weights of the elements contained in the 

 substances, has been applied by A. Benoist to the 

 determination of the atomic weight of indium. 

 He found by this method that if the metal is 

 bivalent its atomic weight is 75.6, but if trivalent 

 it is 113.4. By another process the author found 

 that the atomic weight of indium was nearer to 

 that of silver (108) than to that of arsenic (75). 

 Hence he infers that the higher valency as found 

 by transparency to the Rontgen rays is the more 

 probable one. 



The assumption of the atomic weight of 113 for 

 indium, corresponding to the oxid In 2 O 3 is con- 



