CHEMISTRY. (CHEMICAL PHYSICS.) 



Ill 



chemical activity ; copper, silver, and gold, increas- 

 ing in malleability with increasing atomic weight 

 and decreasing chemical activity. Thus is given a 

 set of relations evidencing the unity of chemical 

 and crystal attractions. 



In an address concerning his investigations with 

 regard to the elements thorium, praseodymium, and 

 neodymium, his revision of the atomic weights of 

 the latter elements, and their probable positions in 

 the periodic table, Prof. B. Brauner drew attention 

 to the scientific importance of further investigation 

 among rare earths, a field of research which prom- 

 ised results of the highest value. Prof. Ramsay, 

 following, pointed out that the work described by 

 Prof. Brauner was a monument of careful experi- 

 ment and extraordinary industry. Although it 

 might appear to many that an enormous amount of 

 labor has been expended on an obscure corner of 

 chemistry, it must be remembered that it was pre- 

 cisely such work which bore upon the whole of 

 chemical theory, and indeed which might be ex- 

 pected to influence chemical manufactures at a 

 future date. 



Writing on the kinetic theory of gases, Prof. 

 Ramsay shows how the observation by Lord Ray- 

 leigh of a discrepancy in the density of atmospheric 

 nitrogen " has resulted in the discovery of a new 

 constituent of air, argon ; its discovery has led to 

 that of a constituent of the solar atmosphere, he- 

 lium ; speculations on the ultimate nature and mo- 

 tion of the particles of which it is believed that 

 gases consist have provoked the consideration of the 

 conditions necessary in order that planets and sat- 

 ellites may retain an atmosphere, and of the nature 

 of that atmosphere ; the necessary existence of an 

 undiscovered element was foreseen, owing to the 

 usual regularity in the distribution of the atomic 

 weights of elements not being attained in the case 

 of helium and argon ; and the source of neon was 

 therefore indicated. This source, atmospheric air, 

 was investigated, and the missing element was dis- 

 covered." 



Reviewing a number of experiments in which nas- 

 cent hydrogen was concerned, D. Tommasi observed 

 that if the properties exhibited by the substance 

 were incident to an allotropic state of the gas, we 

 ought always to obtain the same reactions, whereas 

 the experiments prove that the reducing power of 

 nascent hydrogen varies according to the reaction 

 which has produced it. " And if this gas in the 

 nascent state possesses a greater affinity than in the 

 ordinary state, that is caused simply by the fact 

 that the hydrogen at the moment of being set free 

 is accompanied with all the heat which is produced 

 while it is being set free. Consequently, nascent 

 hydrogen is synonymous with H -f- cal., and the dif- 

 ferences that we observe between hydrogen pro- 

 duced by different chemical reactions have their 

 reason in that these reactions do not all give off the 

 same quantity of heat." 



J. J. Van Lahr attempts to explain a discrepancy 

 in the operation of the law discovered by Ostwald 

 for weak electrolytes in that it does not hold for 

 substances which, like HC1, are to a great extent 

 dissociated in aqueous solution by an assumption 

 supported by several arguments, that the electrical 

 conductivity of a good electrolyte is not an exact 

 measure of its degree of dissociation. He believes 

 that the degree of dissociation of a good electrolyte 

 is modified by the passage of the current, the tem- 

 perature of its ions and molecules being much 

 higher than that of the surrounding medium. 



Chemical Physics. Liquefaction of Hydrogen 

 and Helium. Prof. Dewar communicated his suc- 

 cess in liquefying hydrogen to the Royal Society 

 May 12, and to the Chemical Society May 19, 1898. 

 Be had already, in 1895, contrived an apparatus for 



the production of a jet of hydrogen containing liq- 

 uid, and shown how such a jet could be used to cool 

 bodies below the temperature that could be reached 

 with liquid air: but all attempts to collect the 

 liquid hydrogen had failed. So far, no investigator 

 had improved upon the results then described. He 

 had constructed a larger apparatus on a similar 

 type with the one then used, and on May 10 of the 

 present year hydrogen was liquefied by allowing 

 the gas, cooled down to 205 C. and under a pres- 

 sure of 180 atmospheres, to escape continuously at 

 the rate of from 10 to 15 cubic feet per minute from 

 the nozzle of a coil of pipe in a double silvered vac- 

 uum vessel of special construction surrounded with 

 a space kept below 200 C. Liquid hydrogen be- 

 gan to drop from this vacuum vessel into another 

 doubly isolated by being surrounded with a third. 

 On this occasion 20 cubic centimetres of liquid hy- 

 drogen were collected in about five miuutes ; and 

 on May 12, 50 cubic centimetres were obtained be- 

 fore the hydrogen jet froze up from the solidifica- 

 tion of air in the pipes. The yield of liquid was 

 about 1 per cent, of the gas. Hydrogen in the 

 liquid condition is clear and colorless, showing no 

 absorption spectrum, and the meniscus is as well 

 defined as in the case of liquid air. The liquid is 

 supposed to have a relatively high refractive index 

 and dispersion, and the density appears to be in ex- 

 cess of the theoretical value, 0.18 to 0.12, deduced 

 respectively from the atomic volumes of organic 

 compounds and from the limiting density found by 

 Amagst for hydrogen gas under infinite compres- 

 sion. 



Helium was placed in liquid hydrogen, and a dis- 

 tinct liquid was seen to condense. A similar ex- 

 periment made with the same helium tube in liquid 

 air under exhaustion instead of in liquid hydrogen 

 gave no condensation. It would thus appear that 

 there can not be any great difference in the boiling 

 points of helium and hydrogen. All known gases 

 have now been condensed into liquids which can be 

 manipulated at their boiling points under atmos- 

 pheric pressure in suitably arranged vacuum ves- 

 sels. With hydrogen as a cooling agent, it will be 

 possible to get within 20 or 30 of the zero of ab- 

 solute temperature, arid its use will open up an en- 

 tirely new field of scientific inquiry. 



The study of fluorine has until recently been em- 

 barrassed by its intense chemical activity, which 

 has proved destructive to the vessels in which the 

 manipulation of it was attempted. It has been 

 found, however, that chemical affinities are sus- 

 pended at extremely low temperatures, and this en- 

 couraged the hope, which has been verified, that a 

 means might thus be found for examining this sub- 

 stance in glass vessels. The earlier experiments 

 proceeded on the supposition that fluorine ap- 

 proached hydrogen in volatility. Later investiga- 

 tions give it a critical value only a few degrees 

 lower than that of oxygen, and a position as to vola- 

 tility somewhere between that of oxygen and that 

 of nitrogen. In the experiments of M. Moissan and 

 Mr. Dewar, performed at the Royal Institution, in 

 liquefying fluorine, the apparatus being cooled 

 down to the temperature of boiling liquid oxygen 

 ( 183 C.), the current of fluorine gas passed 

 through without becoming liquid. It had, how- 

 ever, lost its chemical activity at this low tempera- 

 ture, and no longer attacked the glass. On lowering 

 the temperature of the liquid oxygen by exhaustion, 

 a yellow liquid was seen collecting, while gas no 

 longer escaped from the apparatus. At this moment 

 the tube by which the gas had been escaping was 

 stopped, so as to prevent air from entering and 

 liquefying, and the glass bulb soon became full of a 

 clear, yellow liquid, possessed of great mobility. 

 The color of this liquid was the same as that of 



