October 20, 192 1] 



NATURE 



241 



Is Scientific Inquiry a Criminal Occupation? 



I ASK the question because, under the provisions of 

 the Safeguarding of Industries Act, 192 1, which came 

 into operation on October i, scientific workers and 

 the public may be fined one-third of the value on all 

 scientific appliances and on all chemicals — other than 

 sulphate of quinine — imported into this country. Why 

 this quinine salt alone of all chemicals should be free 

 I do not understand, unless it be because it is largely 

 used as a contraceptive and the philanthropic framers 

 of the Act are alive to the fact, which of all others 

 is the most important for us to recognise, that our 

 countr}- has double the population it can carrv. 

 Obviously, they are bent on discouraging and hinder- 

 ing scientific inquiry in even,- possible way ; the Act 

 can have no other effect ; only a small proportion of 

 the articles it covers are, or ever will be, made in thFs 

 country. No more iniquitous measure was ever passed 

 into law. 



I have given notice that at the next meeting of the 

 council of the Chemical Society I will move that 

 action be taken forthwith to secure the repeal of the 

 Act. If it be not annulled, scientific workers generallv 

 must agree to boycott all apparatus and materials of 

 English manufacture. For once we must wake up 

 and show that we can both help ourselves and protect 

 the interests of our countrw 



Sir William Pope, in a recent speech dealing with 

 American conditions, pointed out that chemists at least 

 were so organised in the U.S.A. that they could make 

 their voice heard with effect in the legislature. Here 

 the legislature, bureaucracy in general, does not care 

 a rap for science. A request made by Sir William 

 Pope several months ago to the Board of Trade, on 

 behalf of the Federal Council, that the Council might 

 be heard on the proposed Bill was never more than 

 formally acknowledged. 



If we believe in our craft and its national value 

 we must be militant in its protection. 



I shall be glad to receive names and addresses 

 (written legibly on postcards, p'ease) of those who are 

 willing to join in a memorial to the Prime Minister. 

 If we desire to gain a position for science in this 

 countr}-, it is our duty to show, for once, that we can 

 do something — that we are not mere talkers. 



Henry E. Armstrong. 



55 Granville Park, Lewisham, London, S.E.13. 



Radiation and Chemical Action. 



As regards Prof. Lindemann's criticism of the 

 radiation hypothesis of chemical reactions, namelv, 

 that exposure of an aqueous solution of sucrose ^\us 

 acid to sunlight brings about no sensible increase in 

 speed, two possible ways of meeting the criticism 

 present themselves. The first is to assert that the 

 absorbing power of the water — that is, its screening 

 effect on the molecules of the reactant solutes— is so 

 great that the effective radiation of sunlight is reduced 

 to negligible dimensions in a thin laver. This sug- 

 c:estion was made by the present writer at the Faradav 

 society's discussion on September 28 last. In the light 

 'f Mr. Taylor's experiments, this suggestion is seen 

 o be untenable. The alternative wav of dealing with 

 :he criticism is based on the relativelv small absorp- 

 lon capacity of the reactant solutes as suggested by 

 Mr. McKeown and the present writer (Journ. Amer. 

 Chem. Soc., p. 1304, June, IQ21). In the paper referred 

 to It is shown that a clear distinction must be drawn 

 between photochemical and thermal conditions, the 

 former involving an absorption coefficient term. 

 NO. 2712, VOL. 108] 



Briefly, the treatment of the photochemical jH-ocess is 

 as follows : — 



Consider a layer of sugar solution, cross-section 

 I cm.- and of thickness dx, at a temperature T,. 

 The number of molecules of sugar present is given by 

 pdxIkT,, where p is the osmotic pressure in absolute 

 units. If the layer be acted on by black-body radia- 

 tion of temperature Tj, the total energy of frequency- v 

 absorbed per second is 2aE'.dv.dx, where a is the 

 absorption coeflicient of the sugar. The chemically 

 effective energy absorbed is a fraction 7 of the above, 

 namelv. 



This energy divided by hv gives the number of sugar 

 molecules decomposed photochemically per second, 

 and therefore the fractional number decomposed in 

 the layer per second is 



For the action of sunlight thts must be multiplied by 

 6"/4 = 5-42 X 10-*, where is the apparent angular semi- 

 diameter of the sun. Putting v = 2-86x10'*, Ti = 293° 

 abs., T, = 6ooo° abs., and /> = 22-4/ 342 atmospheres 

 (Taylor's experimental conditions), and giving to dv 

 the probable value 3 x 10", we get the fraction decom- 

 posed per second by the photochemical action to be 

 1-06x10-* a-y. The value of the Ihermal unimole- 

 cular velocit}' constant is approximatelv 4-3x10-*. 

 Whilst actual data on the amount of absorption by 

 the dissolved reactants are lacking, it is evident that 

 the photochemical decomposition may readilv be of the 

 same order as the thermal effect, or even of a smaller 

 CH-der. It certainly does not exceed it by any such 

 impossible magnitude as lo", and it is not surprising, 

 therefore, that, with the ver\- small time of exposure 

 (about I second) given by Mr. Taylor to the droplets 

 of the sugar solution, no appreciable change in the 

 reaction velocity should have been observ^ed. 



A very rough estimate of the order of magnitude of a-y 

 may be obtained as follows : — In the first place, let us 

 set 7=1, its maximum value (in the case of anthracene 

 7 has been estimated by Weigert as 004). As regards 

 o, Coblentz has measured the percentage transmission 

 of solid sugar in the infra-red region. In the neigh- 

 bourhood of i,u the value of o, obtained from 

 Coblentz's data, is 46. In the case of 10 per cent, 

 sugar solution the absorption coefficient, in so far as 

 it depends on the sugar, would be reduced to about 

 one-tenth of this value, corresponding to the ten- 

 fo'd dispersion of the sugar molecules. Hence, in so 

 far as these data are applicable, one would infer that 

 the maximum value of a-y does not exceed 5, thus 

 making the photochemical fractional decomposition 

 at most of the order 5 x 10-*, which is 100 times the 

 thermal for the acid strength emploved bv Mr. Tavlor. 

 .\s the thermal change in i second is quite inappre- 

 ciable, it is possible for the photochemical change to 

 be inappreciable also. (I omit, for the sake of bt-evity, 

 consideration of the fact that the inversion of sugar 

 is not a simple process, but involves at least three 

 consecutive processes, so that the precise value of the 

 effective wave-length has not as yet been ascertained.) 

 .Finally, it may be pointed out that no determination 

 of the amount of radiation absorbed bv the sugar in 

 the solution has as yet been carried out by Mr. Tavlor. 

 If this were small, no chemical change in excess of 

 the thermal change would be anticioated. 



W. C. McC. Lewis. 

 Musoratt Laboraton,- of Physical and Electro- 

 Chemistry-, L'niversity of Liverpool. 



