3o6 



NATURE 



[July 30, 1903 



Wave-lengths of Silicon Lines. — Supplementing his 

 recent work on the wave-length of the magnesium line at 

 A 4481, Prof. Hartmann has now redetermined the wave- 

 lengths of the two silicon lines at \ 4128 and A 4131, and 

 has published his results in No. i, vol. xviii. of the Astvo- 

 physical Journal. 



These two lines, which are of great importance in the 

 discussion of stellar spectra, generally appear broad and 

 hazy in laboratory spectra, but, by photographing the 

 spectrum of Geissler tubes containing silicon tetra-fluoride 

 at low pressure. Prof. Hartmann has obtained them as 

 sharply defined lines, from measurements of which he has 

 obtained 4128-204 and 4131040 as their respective wave- 

 lengths, these values being based on Kayser's wave-lengths 

 for three iron lines, viz. A 4118-709, A 4x32-217 and 

 A 4144033. 



By similar means he has redetermined the wave-length 

 of the carbon line at A 4267, and gives 4267-301 as its exact 

 value. 



The EcLirsE of the Moon, April 11-12. — In the July 

 number of the Bulletin dc la Society Astronomique de France 

 a large number of photographs of this eclipse, obtained by 

 various correspondents of the society, are reproduced. The 

 photographs were obtained with many various instruments, 

 and they, together with the remarks accompanying them, 

 emphasise the exceptional density of the earth's shadow 

 during this eclipse. 



A METHOD OF APPLYING THE RAYS FROM 

 RADIUM AND THORIUM TO THE TREAT- 

 MENT OF CONSUMPTION.' 



"yHE successful results reported in the treatment of rodent 

 cancer by the rays from radium, and the general 

 germicidal action of the rays, make the discoveries and 

 investigations by Prof. Rutherforcl of the radio-active 

 emanations of radium and thorium of great possible im- 

 portance to medical men. The present article deals with 

 the manner in which these emanations can be inhaled into 

 the lungs and be made the means of applying the rays 

 from radium and thorium to the treatment of consumption, 

 in the hope that medical men will be induced to undertake 

 research in this field. The rays from radium and thorium 

 are very similar in kind, but differ greatly in relative degree. 

 Five minutes' application of radium would be about equiva- 

 lent to ten years' application of the same weight of thorium. 

 Both elements continually and spontaneouslv produce 

 radio-active emanations, or gases in infinitesimal quantity, 

 beyond the present means of chemical or spectroscopic de- 

 tection, but endowed with very considerable powers of 

 giving out rays on their own account of exactly similar 

 kind to the rays from radium and thorium themselves. The 

 best condition for the free escape of these emanations, so 

 that they can mingle with the air the patient breathes, 

 occurs with both radium and thorium compounds when they 

 are dissolved in water. In the solid state the emanations 

 are often stored up by the salt and do not escape. Three- 

 quarters of the normal activity of a dry solid radium com- 

 pound is due to the stored up emanation. This escapes 

 into the air instantly when it is dissolved in water. 



If the air containing the emanation is removed and stored 

 in a gas-holder away from the radium, the quantity slowly 

 diminishes, and the radium solution grows a fresh crop 

 as fast as the old disappears. In four days one-half of the 

 emanation removed has disappeared, and one-half has re- 

 appeared in the vessel containing the radium solution, pro- 

 vided, of course, that it has been closed air-tight in the 

 interval. After about three weeks the amount of the old 

 emanation remaining is negligibly small ; the amount re- 

 formed is a practical maximum, the same as was originally 

 obtained on dissolving the solid salt. In the case of 

 thorium one-half of the emanation disappears or is repro- 

 duced, as the case may be, in one minute. In five minutes 

 the old emanation has practically all disappeared, and the 

 thorium solution, if kept in a closed bottle, again contains 

 as much as it ever did or can contain. In three weeks for 

 radium, and in five minutes for thorium, an equilibrium in 

 the amount of emanation present is reached, as much dis- 

 1 Abridged from the British Medical Journal, July 25. 

 NO. 176 I, VOL. 68] 



appearing as is reproduced, in the same way as the popula- 

 tion of a country remains constant when the number of 

 births in any given time equals the number of deaths. 



These considerations regulate the " dosage." The longer 

 a patient breathes through a thorium solution the greater 

 th° dose of emanation. With radium, however, once the 

 emanation has all been inhaled, no further effect is pro- 

 duced, and the solution must be left tightly closed to re- 

 cover its emanation before it can again be advantageously 

 used. Further, in dealing with the thorium emanation, it 

 is essential that the air should reach the patient's lungs 

 within the shortest possible time, say half a minute, after 

 leaving the thorium solution. 



The property of the emanations of leaving behind a film 

 of radio-active matter wherever they come into contact, 

 which causes the phenomenon of " excited " or " induced " 

 radio-activity, is important in the present connection, 

 because this excited activity will remain in the air-cells of 

 the lungs after the emanations themselves have been ex- 

 haled. This excited activity gradually disappears in the 

 course of time, becoming negligible with thorium after two 

 days, and with radium after three or four hours. The 

 practical effect of this in both cases will be to cause a 

 feebler continued action of the rays on the lungs after the 

 more powerfully radio-active emanations have all been 

 exhaled. 



Which emanation will prove the more suited for the pre- 

 sent purpose is, of course, a matter for trial, but thorium 

 possesses many compensating advantages which make up 

 for its very feeble radio-activity. It is cheap, and can be 

 procured in any quantity. Unl'ike radium, the effect of its 

 emanation is proportional to the time of inhalation. More- 

 over, in dealing with the emanation there is practically no 

 limit to the quantity effectively employable. The radiation 

 from a solid salt, owing to absorption of the rays by the 

 salt itself, is practically confined to a thin surface layer, 

 but with the emanation no such absorption occurs. The 

 emanation from a kilogram or more of thorium salt could 

 be effectively employed on the lungs of a single patient. 

 Thorium nitrate, a very soluble salt, is the most suitable 

 compound to employ, but the free nitric acid present should 

 be neutralised after the salt has been dissolved in water by 

 cautious addition of ammonia with stirring, until precipita- 

 tion is about to take place. A gas washing bottle, with 

 outlet and inlet tubes ground in, could be used as the in- 

 haler, and this should be filled as full as possible with the 

 moderately concentrated solution. There is not much fear 

 that an hour's daily inhalation of the emanation from 100 

 grams of dissolved thorium nitrate would produce any ill 

 effect, and both the quantity employed and the time of 

 inhalation could, after due trial, be increased indefinitely. 

 For use with the radium emanation the inlet and outlet 

 tubes should be provided with taps. A few milligrams of 

 the salt, radium bromide, for example, should be placed 

 in the dry bottle, and water drawA in "to dissolve it, the 

 taps being then closed. For the first trials, a few bubbles 

 only of the total gas contained in a fairly large bottle should 

 be drawn into the lungs with a deep breath of air, and re- 

 tained as long as possible before being exhaled. The dose 

 should be only very gradually increased, and the effect on the 

 system very carefully watched, for the radium einanation 

 is an exceedingly powerful agent. Mixed witfc £fir it glows 

 brightly in a dark room, and exerts a very rapid oxidising 

 action on carbonaceous matter, and even on mercury. The 

 maximum possible dose for any one quantity of radium 

 solution would be obtained by inhaling the whole gaseous 

 contents of the bottle, a few bubbles at every breath, once 

 every twenty-four hours. 



The immunity of these processes from external- inter- 

 ference, the simple nature of the treatment proposed, the 

 infinitesimal quantity of the active agents employed, the 

 manner in which the emanations may be inhaled to do 

 their work at the very seat of the disease, leaving behind 

 in their place the excited activity to continue the work in 

 a gentle manner after they have been exhaled, make out 

 a strong case why the attention of medical men should be 

 directed to these new weapons which physics and chemistry 

 have placed at their disposal. Indeed, if nature had de- 

 signed these phenomena for the purpose proposed, it is 

 difficult to see in what way they could be improved upon. 



Frederick Soddy. 



