November 5, 1908J 



NA TURE 



gauge, in the construction of which no india-rubber joints 

 were used, the mercury reservoir being connected to an 

 exhaust pump, while the elevation and lowering of the 

 mcrcurv was carried out by admitting and exhausting air 

 in the' reservoir. The air coming in contact with the 

 mercury was purified by passage over stick-potash and 

 phosphoric anhydride. Scaled on to the gauge was a long 

 U-tube containing a \ gram of cocoa-nut charcoal placed 

 in a small enlargement at the bend, the whole being 

 arranged for liquid air or other cooling for any desired 

 length of time. The object of the use of this cooled 

 charcoal is to take up and condense all adventitious gases, 

 other than hydrogen or helium, which might arise from 

 minute leakage or otherwise be generated in the 

 apparatus. 



Starting with an exhaustion of 0-000054 mm. in iioo 

 hours, apart from intermediate irregularities, the total 

 quantity of permanent gas produced per gram of radium 

 per day did not exceed 042 cubic mm. As in this experi- 

 ment the emanation had free play over the whole surface 

 of the McLeod gauge during a fortnight when the labora- 

 tory was closed, a second one was carried out, keeping 

 ihe charcoal U-tube in liquid air during the whole course 

 of the observations, which lasted six weeks. It was now 

 found that, with the exception of the occlusion of the 

 helium in the radium salt and its immediate surroundings, 

 all the anomalies of the first experiment had disappeared, 

 and the steady increment of helium (as shown by the 

 graphical diagram given in the paper) amounted to 037 

 cubic mm. The spectroscopic examination of the gas 

 showed that the helium was pure, and this result was con- 

 firmed by observing the reduction in pressure caused by 

 cooling the radium salt and also the charcoal in liquid 

 hydrogen. 



The author is not aware of any previous direct measure- 

 ments of the rate of production of helium from radium, 

 but in a paper on " Some Properties of Radium Emana- 

 tion," by A. J. Cameron and Sir William Ramsay (Chem. 

 Soc. Jour., 1907, p. 1274), the ratio of the amount of 

 helium produced to that of the emanation was found to be 

 3-18, and as the amount of the emanation found by them 

 was about i cubic mm. per gram of radium per day, the 

 resulting helium, according to this experiment, ought to 

 reach about 3 cubic mm., or at least eight times the rate 

 of production found in the above experiments. The 

 author is at a loss to explain the origin of such grave 

 discrepancies in the measured amount of the helium pro- 

 duced by radium.' On the other hand, Prof. Rutherford, 

 in his work entitled "Radio-active Transformations," 

 igo6, p. 186, on the theoretical assumption that the a. 

 particle is an atom of helium carrying twice the ionic 

 charge, deduced from electrical measurements that the 

 number of particles expelled per year per gram of radium 

 would reach 4X10'*, and as i c.c. of a gas at standard 

 temperature and pressure contains 3-6x10" molecules, 

 the volume of helium produced per year would amount 

 to o-ii c.c, which is equivalent to about 0-3 of a cubic 

 mm. per dav. Considering that the author has found a 

 rate of helium production of the order of 0-37 cubic mm., 

 the agreement between experiment and the theoretical 

 prophecv of Rutherford is almost too wonderful, sub- 

 stantiating as it does the accuracy of the theory of radiq- 

 active changes he has done so much to initiate and 

 develop. 



PaT!IS. 



Academy of Sciences. Octnh-r 26. — M. li'nirhnrH in ihe 

 chair. — Observations of the comet 1908c made at the 

 Observatory of Bordeaux with the 38 cm. equatorial : Luc 

 Picart. The observations were made on the nights of 

 October 7, 10, 12, 13, and 17, the apparent positions of 

 the comet and the positions of the comparison stars being 

 given in tabular form. From October 7 to 18 the comet 

 appeared as a feeble nebulosity, without a nucleus, render- 

 ing the determination of its exact position difficult. On 

 October 12 the tail was clearly visible, with a length of 

 about two degrees ; on the following night the comet pre- 



1 Prof. Rulh*rford, in .t p.-iper, " Experinr'nts with R.-idium EmanaMon." 

 Phil. Mag., July, 1908. shows this result is at least ten limes too sreat, his 

 value belnp nf the order o'li cub. mm. of emanation per day, whereas frorn 

 the author's experiments the rate of helium production is just three times this 

 amount. 



NO. 2036, VOL. 79] 



sented its usual form. — Observations of thg comet igoSr 

 made at the Observatory of Marseilles with the Eichens. 

 26 cm. equatorial : M. Borrelly. Details are given of 

 observations made on September 12, 15, 16, 17, and 

 October 2 and 3. The changes in form were studied by 

 moans of seven photographs. — A first series of photographs 

 of the Morehouse comet obtained with the large telescope 

 at Meudon : L. Rabourdin. These photographs were 

 taken on the nights of October 14, 16, 17, 20, 22, and 23 

 with the telescope of i metre aperture. The photographs 

 do not indicate the complete development of the comet, 

 but show the nucleus and portions of the tail. The central 

 nucleus appears to be surrounded by several envelopes, 

 each having its prolongation on the side opposed to the 

 sun. — k theoretical explanation of the experiments of M. 

 Birkeland : Carl Stormer. Four photographs are given 

 showing a wire model representing a kathode bundle under 

 the action of a small magnetic globe. — Contribution to 

 the study of lenses : G. Maltezos. A theoretical investi- 

 gation of the equations between the distances of the lens, 

 supposed spherical, from the first luminous point and its 

 secondary images produced by successive reflections and 

 refractions at the surfaces of the lens. — .A monotelephone 

 of great sensitiveness and with its note capable of regula- 

 tion : Henri Abraham, k modification of the Mercadier 

 telephone, in which the soft iron plate is replaced by a 

 strong disc of tempered steel. The Mercadier disc is re- 

 placed by a small sheet of iron, just sufficiently large to 

 cover the electromagnet, and this is carried by two parallel 

 steel wires. With a rhythmic current in unison with the 

 proper note of the instrument the sensibility is much 

 greater than with ordinary telephones. The note can be 

 varied at will by altering the tension of the steel wires. — 

 Induction and the probable cause of polar aurora : P. 

 Villard. — The magnetic properties of metallic oxygen 

 radicals : P. Pascal. .A study of the magnetic properties 

 of salts of metals which form both acid and basic oxides. 

 — Mercurous nitrate as a microchemical reagent for 

 arsenic : G. Denises. The arsenic compound is converted 

 into arsenic acid, and drops of this solution submitted to 

 the action of a solution containing 10 grams of crystal- 

 lised mercurous nitrate, 10 c.c. of nitric acid of specific 

 gravity 1-39, and 100 c.c. of distilled water. Characteristic 

 crystals are produced. The smallest amount of arsenic 

 observable by this method is not stated. — Some oxydase 

 phenomena produced by colloidal iron ferrocyanide : J. 

 Wolff. — The action of bromine on ether : monobrom- 

 aldehvde : Ch. Maugruin. Bromine reacts on moist ether 

 in presence of light, considerable quantities of monobrom- 

 aldehyde being produced. The aldehyde is best isolated 

 by means of the condensation compound formed with 

 urethane, the yield being sufficiently good for the reaction 

 to serve as a good method of preparation of this aldehyde. 

 — New researches on bakanosine : Em. Bourauelot and 

 H. Herissey. This glucoside is extracted from a 

 Strvchnos called Bakanico by the natives of Majunga, 

 Madagascar. The physical and chemical properties of the 

 pure alkaloid are given, the formula being 



C„H,30,N4-H,0. 



— The transformations of the chromogenic material of 

 grapes during ripening : J. Laborde. — Cedrelopsis : M. 

 Costantin and H. Poisson. — The preservation of the 

 cocoa-nut : M. Dybowski. The present method of treat- 

 ing copra causes serious deterioration owing to the action 

 of micro-organisms on the albumin and fat. It has been 

 found that this can be entirely prevented by treating the 

 copra with gaseous sulphur dioxide. — The Plumulariidae 

 of the Challenger collection : Armand Billard. — The 

 mobility and dissemination of infected dust due to the 

 disturbance of dried tuberculous sputum : G. Kiiss. A 

 study of the mode of dissemination of infected dust, pro- 

 duced by slowlv drying the sputum of tuberculous patients 

 in the dark under conditions approximating to those which 

 occur in practice. The quantity of infected dust produced 

 is very small compared with the quantity of sputum. 

 When the dust is caused by slight shaking or beating of 

 an infected carpet, these powders are only projected for 

 a short distance above the carpet. They are, however, 

 sufificiently light to remain in suspension in the air for from- 



