April 20, 1905] 



NA TURE 



597 



secretion of hydrochloric acid by the gastric aflands is a 

 decrease in the concentration of the hydrogen ions. 



Blood plasma is alkaline to some indicators and acid 

 to others, indicating the presence of both hydroxyl ions, 

 upon which its alkalinity depends, and hydrogen ions, 

 giving an acid reaction. Any agency which increases the 

 effective alkalinity of the blood, that is to say, which in- 

 creases the hydroxyl ions and diminishes the hydrogen 

 ions, will increase the difficulty of separating a secretion 

 containing free hydrochloric acid. 



In cases where the gastric secretion has its acidity 

 diminished or reduced to zero, as is found to be the case 

 in carcinoma, it is hence highly probable that the cup- 

 oentration of the hydrogen ions in blood plasma is re- 

 duced. The action of the kidney cells in maintaining a 

 definite degree of alkalinity of the plasma is hence altered, 

 so that a greater degree of alkalinity is maintained than 

 in the normal individual. 



It has been shown by Loeb that slight increase in 

 alkalinity of the medium leads in certain instances to a 

 more rapid cell division and growth, and if this holds 

 good generally, it is possible that increased alkalinity of 

 the blood plasma may lead to increased activity in cell 

 division, and hence be a stimulating cause leading to 

 formation of new growths. 



The acidity was determined by the following methods : — 



(17) Total acidity by titration with phenolphthalein as 

 indicator. This lay very low in the seventeen cancer cases, 

 being normal in one case only, above oi per cent, in four 

 cases, and in the majority one or two drops of decinormal 

 alkali sufficed to render neutral. 



(b) GUnzberg's reagent for free hydrochloric acid gave 

 entire absence in eleven out of seventeen cases, a minute 

 trace in five cases (00036 per cent, to 00109 per cent.), 

 and 00365 per cent, was the highest value attained in a 

 single case only. 



(c) Hydrolysis of methyl acetate by the filtered gastric 

 contents for the determination of the concentration of free 

 hydrogen ions was carried out in ten cases, and it was 

 found that the concentration in all these never exceeded 

 one-fifteenth of the average concentration in three normal 

 cases tested by the same method. 



March 30. — " Note on Fluorescence and Absorption." 

 By J. B. Burke. Communicated by Prof. Larmor, 

 Sec.R.S. 



In a paper " On the Change of Absorption produced by 

 Fluorescence " ' the author gave an account of the experi- 

 ments by which he found the existence of a very remark- 

 able difference in the absorption of the fluorescent light of 

 uranium glass when in the luminous and non-luminous 

 states. This difference he has attributed " to a temporary 

 change in structure or chemical composition of the body 

 when exposed to the influence of the exciting light, and 

 he has been led to regard this as due to new atomic con- 

 nections giving rise to new frequencies during the 

 period of luminosity, by the formation of unstable aggre- 

 gates, which radiate intensely, as they disintegrate, the 

 energy which was stored up in their formation ; the 

 luminosity being thus the visible manifestation of a process 

 of building up and breaking down of molecules. 



Messrs. Nichols and Merritt have found recently' that 

 the change of absorption depends upon the intensity of the 

 fluorescence, and that a saturation effect takes place in 

 the absorption as the intensity of the luminosity increases, 

 attaining a maximum with a certain intensity of the fluor- 

 escent light. They used, not the fluorescent light from 

 another similarly excited body, but an acetylene flame as 

 the source of the transmitted rays. 



M. Camichel has encountered some difficulty in detect- 

 ing the change with the light from a flame, and this 

 appears to have been due to the use of a screen of 

 uranium glass, 7 cm. in thickness, to cut off the more 

 refrangible rays from the flame, a precaution which is by 

 no means necessary, since the effect has been observed 

 without it. The fluorescence caused by the flame merely 

 diminishes the apparent absorption. The screen, on the 

 other hand, must itself fluoresce, and in so doing — if the 



Pkilosophtcal Transactions^ (A) i8q8 ; 

 British As>oc. Report, Belfast, iqo2, a 

 Physical Rcviciu, December, 1904. 



NO. I 85 I, VOL. 71] 



Nature, July . 

 id Phi!. Mag , II 



effect sought for occurs — absorb to a considerable extent 

 the rays the absorption of which it is proposed to measure 

 on the assumption that they are transmitted by the screen. 



For fluorescence of very feeble intensity the effect may 

 not in any circumstances be perceptible. 



Furthermore, the fluorescent spectrum of uranium glass 

 is composed of several bands, and these in turn the 

 author regards as discontinuous, and made up of more 

 finely divided bands or lines. 



Thus the use of the screen filters the rays, and only 

 those which are not absorbed by uranium glass are trans- 

 mitted. These would not undergo any change of absorp- 

 tion. 



The change of absorption cannot be due to the increased 

 amplitude if the vibrations are linear, but where new free 

 periods are produced by the exciting rays, the intensity 

 and the absorption of the fluorescent light would both 

 depend upon the number and duration of the periods thus 

 produced, and it is this which the change of absorption 

 in fluorescence most distinctly proves. 



" The Direct Synthesis of Ammonia." By Dr. E. P. 

 Perman, Communicated by Principal E. H. Griffiths, 

 F.R.S. 



(i) So far as can be shown by one of the most delicate 

 tests known to chemists, ammonia cannot be synthesised 

 by heat (except under special conditions specified below). 

 The decomposition of ammonia by heat may, therefore, be 

 regarded as an irreversible reaction. (2) Ammonia may 

 be synthesised in small quantities from its constituent 

 elements (a) by heating with many of the metals ; (b) by 

 exploding with oxygen ; (c) by sparking. These are re- 

 versible reactions. (3) It would appear that the synthesis 

 of ammonia is effected only when the gases are ionised ; 

 the ionisation would be brought about by sparking, or by 

 the high temperature of an explosion of hydrogen and 

 oxygen. The immediate decomposition of the ammonia 

 formed would be prevented by its sudden cooling. The 

 metals in the presence of moisture also produce " nascent " 

 or ionised hydrogen. (4) It does not appear that nitrides 

 of the metals form an intermediate stage in the formation 

 of ammonia, for it was found that metals readily forming 

 nitrides, e.g. magnesium, did not produce more ammonia 

 than the others. (5) There is a close analogy between 

 ozone and ammonia with regard to their synthesis and 

 decomposition ; both are formed by sparking, and both 

 are completely decomposed by heat. 



" Determination of Vapour-pressure by Air-bubbling." 

 By Dr. E. P. Perman and J. H. Davies. Communicated 

 by Principal E. H. Griffiths, F.R.S. 



It was shown recently by one of the authors that the 

 vapour-pressure of water can be determined with a con- 

 siderable degree of accuracy by bubbling a current of air 

 through water in a thermostat, and estimating the amount 

 of water evaporated by absorbing it in strong sulphuric 

 acid. 



The accuracy of the method has since been questioned, 

 supersaturation being specially suggested as likely to cause 

 error. Experiments have therefore been made in order to 

 discover what error (if any) is introduced by super- 

 saturating the air with moisture before it enters the water 

 in the thermostat. The effect of dust in the air and of 

 electrification have also been investigated. In each case 

 the arrangement of the apparatus was as described in the 

 previous paper. 



Supersaturation. — Before passing into the flasks in the 

 thermostat, which was inaintained at 70°, the air was 

 bubbled through a large wash-bottle containing water at 

 about 85°. 



Dust in the Air. — A thick smoke was made by burning 

 pieces of phosphorus near the inlet tube of the apparatus 

 described in the former paper. 



Electrification of the Air. — (i) The air was made to pass 

 through a large flask in which hydrogen was being rapidly 

 evolved from zinc and dilute sulphuric acid. 



(2) One terminal of an induction-coil, capable of giving 

 (with the battery power used) a 6-inch spark, was con- 

 nected with a wire passing into the first (nearest the inlet) 

 I flask in the thermostat ; the other terminal was connected 

 with the bath, so that the silent discharge passed through 

 the flasks and the air inside. 



