August i, 1895] 



NA TURE 



il^ 



C. N. Hooper referred to the work done by the London 

 Chamber of Commerce, and the discussion was continued by 

 Messrs. PhilUps, Burgess, Batalha Reis, and Vule Oldham. 

 The President proposed that a committee, consisting of Chief 

 Justice Daly (chairman), I'rof. Levasseur, Prof Lehmann, Mr. 

 Mackinder, and Mr. Herbertson, should be appointed to consider 

 a resolution on geographical education, to be submitted to the 

 Congress. 



Section C, which met at the same time, concerned itself with 

 photographic surveying. The presidential chair was occupied 

 by Prince Roland Bonaparte and (General Walker jointly. In a 

 paper read on his behalf by M. Schrader, Colonel Laussedat 

 considered the application of photography to the rapid deter- 

 mination of points in levelling, and a combined camera and theo- 

 dolite was exhibited. M. de Dechy, in discussion, insisted that 

 photography must always be merely auxiliary to triangulation, 

 and must not in any way replace i( ; and Mr. Coles described 

 his work in constructing a map of the Caucasus from photo- 

 graphs alone. Captain E. H. Hills then read a paper on the 

 determination of terrestrial longitudes by means of photography, 

 in which he described improved methods of exposing and 

 measuring plates used in photograph.ing lunar distances, by 

 means of which he had obtained better results than those 

 obtained by Schlichter and Runge. An abstract of a paper 

 by Prof \. Thoulet, suggesting the extended application of 

 photography to the survey of rapidly shifting sandbanks, was 

 read in his absence. Mr. Coles described and exhibited Colonel 

 Stewart's camera for producing photographs of the whole horizon, 

 and the proceedings closed with an informal communication by 

 M. Janet on the determination of longitudes without instruments 

 of precision. 



HELIUM, A CONSTITUENT OF CERTAIN 

 MINERALS} 



n. 



( H. ) The Properties of Helium. 



17 ROM what has preceded, it appears that up to now only three 

 mineralsareavailableassourcesof helium, unless, indeed, very 

 large quantities of samarskite and yttrotantalite are worked up. 

 These three arecleveile, the iiraninile investigated by Hillebrand, 

 and broggerite. .'Vnd here we wish to express our indebtedness 

 to Prof Hrogger for his great kintlness in placing a large stock of 

 brc)ggerite at our disposal. It has furnished a large quantity of 

 the helium which we have had in our hands. 



.Mthough, so far as we were able to judge by throwing into a 

 two-prism spectroscope of Browning's the spectra of samples of 

 gases obtained from the minerals previously mentioned, all the 

 specimens of helium were identical, still a further proof was 

 desirable. Owing to the small quantities of gas yielded by these 

 minerals, amounting in most cases to a few c.c. , it was impossible 

 to ascertain whether these samples were of the same density : 

 but the case was different with the gas from cleveite and from 

 broggerite. In each case a sufficient quantity was obtained to 

 make it possible to determine the density with fair accuracy. It 

 will be convenient therefore to describe the methods of extracting 

 the gas and the methods determining its density. 



In the communication to the Royal .Society it was stated that 

 the maximum density of the original gas from cleveite was 3 "89. 

 The spectroscojie showed the presence of nitrogen in this sample ; 

 the bands were very l»rilliant at high pressure, but on reducing 

 the pressure the yellow line became brilliant, and the nitrogen 

 spectrum disappeared. This alwayshappens when the lube has 

 platinum electrodes and a strong discharge is passed for a con- 

 .siderable time.- An attempt was made to remove the nitrogen 

 from this sanqilc of gas by circulating it over red-hot magnesium ; 

 but an unfortunate accident caused the admixture of about its 

 own volume of air, carrying with it argon, from which at present 

 there is no known method of separating helium. 



It appeared important to deciile whether the gas evolved from 

 these minerals is helium, or a compound of hydrogen and 

 helium ; for in the preliminary set of experiments the treatment 

 was such that a hydride would have been decomposed either 

 by sparking with oxygen or by jiassage over copper oxide at a 

 red heat. 



> .\ paper by Prof. \Villi.im R.-ims,-iy, F.R.S., Dr. J. Xorman Collie, and 

 Mr. Morns Travers, read before the Chemical Society on June 20. (Continued 

 from p. 308.) 



NO. 1344, VOL. 52] 



The result of experiments directed to this end is to show that 

 no combined hydrogen is present. Gas was extracted from 

 nineteen grams of broggerite by heating it in a combustion-tube 

 to dull redness ; the combustion-tube was connected with a 

 Tiippler's pump by means of thick-walled india-rubber tubing, 

 wired carefully. Special experiments showed that the leakage 

 through the india-rubber amounted between Saturday and 

 Monday to less than one small bubble. The broggerite 

 yielded about 75 c.c. of gas, a large portion of which was 

 absorbed by caustic soda, leaving about 35 c.c. \ second 

 charge of i8-3 grams gave 585 c.c, and a third, of 22'i grams, 

 gave 66 'O c.c. The amount of gas evolved depends largely on 

 the temperature. The evolution is rapid at first, but becomes 

 very slow after three hours, and the heating was always stopped 

 before all the gas which might have been extracted had come 

 off. The last portions, as will be seen later, were extracted by 

 fusion with hydrogen potassium sulphate. 



This crude product from broggerite blackened mercury, 

 doubtless owing to the presence of hydrogen sulphide. 



The density of this sample was determined ; the data are 

 these. 



Volume of bulb 33023 c.c. 



Temperarure ... ... ... ... 22'9 



Pressure (corr.) ... ... ... 7667 mm. 



Weight... 0'0327 gram 



Density (0 = l6) ii-go 



The exceedingly small capacity of the bulb calls for some 

 remark, hut for no apology. The object here is, not to 

 determine the density with the utmost accuracy, but to secure a 

 guide, sufficient for our purpose, which will indicate the prob- 

 able molecular weight. Now the hydrogen contained in such a 

 bulb at 0° and 760 mm. weighs approximately 0'0030 gram. 

 A sensitive balance by Oertling, adjusted for the special purpose, 

 could easily be read to o"oooo5 gram, without resorting to the 

 the reading of oscillations of the pointer ; and this gives an 

 accuracy of 5 parts in 300, or i 7 per cent. Hence the density 

 of hydrogen, thus determined, might vary between 0-983 and 

 I '017. It is evident that such an approximation is quite 

 sufficient for our present purpose. The total volume of this 

 gas was 124'5 c.c. A solution of soda was introduced by 

 means of a pipette, and after all absorption had ceased, 

 the residue measured 78-0 c.c. The density was again 

 determined. 



33-023 c.c. 

 21-6' 



\"oIume of bulb 

 Temperature ... 



Pressure (corr.) 765 '4 mm. 



Weight o'oo58 gram 



Density (0= 16) 2105 



This gas was now left in contact with palladium sponge for a 

 night. The sponge was made by reducing the chloride in a 

 current of hydrogen, at a dull red heat. As it was some- 

 what porous, it was hammered on a steel anvil before intro- 

 ducing it into the gas, which, of course, was confined over 

 mercury. The contraction amounted to abont l/30th. The 

 density was again taken. 



Volume of bulb ... ... ... 33-023 c.c. 



Temperature ... ... ... ... 19-2° 



Pressure (corr. ) ... ... ... 760-2 mm. 



Weight o-cx)630 gram 



Density (0= 16) 2-284 



This gas had undergone no treatment which was of a kind to 

 remove combined hydrogen, unless, indeed — a very iuqirobable 

 assumption — it be supposed that the compound should be 

 decomposed by contact with metallic palladium. The gas was 

 therefore placed in contact with copper oxide, which h.->d 

 previously been heated to redness in a vacuum, and a tube filletl 

 with (ihosphoric anhydride was so interposed as to alisorb any 

 water produced. The gain in weight of this tube was 0-0016 

 gram, indicating the oxidation of about 2 c.c. of hydrogen. In 

 all probability this hydrogen had remained over after treatment 

 with palladium ; for it bears no proportion to the total quantity 

 of gas — 78 c.c. 



The density was again determined. 



Vohnne of bulb ... ... ... 33-023 c.c. 



Temperature ... ... ... ... 1667' 



Pressure (corr. ) 754-9 mm. 



Weight 0-00720 grant 



Density (O- 16) 2606 



