CHEMISTRY. 



109 



ng i* insullicien* t<> onablo him to undcr- 

 the nature "f tin 1 changes which occur in 

 .if his operations, he can not derive 

 : vantage from t. clinical instruction. Th.-c 

 .1. I hojH-, servo to emphasize a dis- 

 n which exists between technical chem- 

 nd other technical subjects . . . Thereason 

 f..r this difference in the mode of treatment of 

 chemical subjects is not difficult to find. The 

 technologist the man who is engaged 

 i he manufacture- of useful products out of 

 tain mw materials is, so far as the purely 

 ntitle principles are concerned, already at a 

 advanced stage, although he may not real- 

 tins to bo the case. The chemistry of manu- 

 uriuir operations, even when these are of an 

 arcntly simple kind, is of a very high order 

 complexity. There are many branches of 

 mical industry in which the uature of the 

 chemical chanires undergone by the materials is 

 imperfectly understood; there is no branch 

 chemical industry of which the pure science 

 be said to be thoroughly known. For these 

 ns I believe that I am justified in saying 

 t the chemical technologist is working at a 

 igh level, so far as the science of his subject is 

 concerned, and this explains why he can not be 



t with by the analytical method." 

 .MM. Lecoq de Boisbaudran and A. de Lap- 

 ?nt claim priority in the discovery of the pe- 

 ic law of the chemical elements for M. Begu- 

 de Chancourtois, Chief Engineer and Assist- 

 t Professor of Geology in the School of Mines, 

 o, on April 7, 1862, presented to the Academy a 

 r " On a Natural Classification of the Simple 

 dical Bodies entitled ' The Telluric Screw,' " 

 (1 followed it with other communications. The 

 in ic screw was a device for graphically repre- 

 ting the relations of the atomic weights, from 

 examination of which it appeared that those 

 .tions corresponded for the most part to real 

 analogies in the properties of the corresponding 

 elements. Mr. John Newland's first publication 

 on the subject was made July*30, 1864, the pub- 

 lications of Profs. Mendeleef and Lothar Meyer 

 ;heir independent and simultaneous discov- 

 of the same truth were made later, 

 hose compounds are called tautomeric by 

 r which apparently react in a manner indi- 

 cated by two constitutional formulae differing 

 from one another. It is assumed that in such 

 bodies the atoms oscillate between two different 

 portions of equilibrium. This interpretation 

 does not permit the use of the term constitutional 

 formula in its proper sense which would permit 

 "y one of those positions recognized from allied 

 tions) to be considered correct. The other 

 position would not belong to the substance per 

 c, because the reactions according to which it 

 has been derived have caused a change of posi- 

 tion of the atoms within the molecule. Incor- 

 rect formulation of the chemical equations for 

 these reactions may be the reason for the appar- 

 ent contradiction of the principles of structural 

 chemistry which these phenomena of change 

 within the molecule offer. 



In his presidential address before the Institu- 

 tion of Klcctrical Engineers, Dr. William Crookes 

 spoke of electricity as a tool by the judicious use 

 of which we may gain some addition to our 

 scanty knowledge of the atoms and molecules of 



heat 



? 



Laa 



lorn 



S 



matter, and of the forms of energy which by 

 their mutual reactions constitute the universe as 

 it is manifest to our five senses. Working as a 

 chemist in the laboratory, the author had found 

 the induction spark often of great service- in dis- 

 criminating one element from another, as well 

 as in indicating the presence of hitherto un- 

 known elements in other bodies in quantities far 

 too minute to be recognized by any other mean?. 

 In this way chemists have discovered thallium, 

 gallium, germanium, and numerous other ele- 

 ments. On the other hand, in the examination 

 of electrical reactions in high vacua various rare 

 chemical elements become in turn tests for recog- 

 nizing the intensity and character of electric 

 energy. Electricity, positive and negative, effect 

 respectively different movements and luminosi- 

 ties. Hence the behavior of the substances upon 

 which electricity acts may indicate with which 

 of these two kinds we have to deal. In other 

 physical researches both electricity and chemistry 

 come into play simply as means of exploration. 



Chemical Physics. A laboratory of low 

 temperatures has been established by Prof. Pictet 

 at Berlin by the aid of which new conditions 

 for investigating the properties of matter are 

 realized, and new facts have been broiight to 

 light in various branches of science. The re- 

 frigerating machinery is designed to withdraw 

 heat from the objects under observation, and to 

 keep them as long as may be required at any de- 

 sired temperature between 20 and 200 C. 

 Of the refrigerating processes at the command 

 of the experimenter, that by the evaporation of 

 liquids is preferred. The < apparatus is adapted 

 to the production of three stages of low tem- 

 perature, for each of which special machinery 

 is provided. For the first stage the Pictet 

 liquid a mixture of sulphurous and carbonic 

 acids is used ; for the second, laughing gas ; for 

 the third stage, liquefied atmospheric air, the 

 evaporation of which causes the thermometer to 

 fall below 200 C. Under the experiments with 

 these apparatus a remarkable difference was 

 noticed in the radiation of heat. Material con- 

 sidered as non-conducting does not appear to 

 affect much the passage of heat into a boay cooled 

 down to below 1(K) ; or, as Prof. Pictet ex- 

 presses it, " the slow oscillations of matter which 

 constitute the lowest degrees of heat pass more 

 readily through the obstruction of a so-called non- 

 conductor than those corresponding to a higher 

 temperature, just as the less intense undulations 

 of the red light are better able to penetrate 

 clouds of dust or vapor than those of the blue." 

 It is mentioned, as an example of the methods 

 which the refrigerating machine permits the in- 

 vestigator to employ, that, in order to measure 

 the elasticity of mercury, Prof. Paalzow had the 

 metal cast into the shape of a tuning-fork and 

 frozen hard enough for the purpose in view. On 

 this occasion it appeared that quicksilver can bo 

 shown in a crystallized state in fern-like crvstals. 

 The most important application of the refriger- 

 ating machinery is in the purification of chloro- 

 form, by which that exceedingly unstable sub- 

 stance becomes a practical 1\ unchangeable liquid. 

 Sulphurous ether is also produced in a hitherto 

 unknown degree of purity. 



Liquid oxygen has l>een hitherto described as 

 colorless, and so it appears to be in thin layers ; 



