174 



NA TURE 



[June 23, 1898 



LETTERS ^ TO THE EDITOR 

 [The Editor does not hold himself responsible for opinions ex 

 pressed by his correspondents. Neither can he undertake 

 to retm-n, or to correspond -with the writers of, reject ei 

 manuscripts intended for this or any other part of Nature. 

 No notice is taken of anonymous coininunicanons.'] 



Liquid Hydrogen. 



In his letter published in your issue of the 9th inst., replying 

 to mine published on May 26, Prof. Dewar does not question 

 the accuracy of the following statements, which form the most 

 important part of my letter : (i) That the combination which I 

 described in that letter as constituting the self-intensive method 

 ot refrigeration was proposed by me at the Royal Institution to 

 his chief assistant, Mr. R. N. Lennox, in November 1894 ; 



(2) that this combination had not been previously employed ; 



(3) that it formed the chief novelty of Prof. Dewar's paper and 

 experiments of December 1895 ! U) that it is essential to the 

 apparatus which has made the step from liquid air to liquid 

 hydrogen. These facts make a sound claim on my part to the 

 invention of the process and to recognition in historical or ex- 

 planatory accounts of work which involves the use of the pro- 

 cess. Prof. Dewar says : " My results would have been attained 

 had Dr. Hampson never existed, just as they have been de- 

 veloped." On the other hand, at the Society of Arts (see 

 journal, March 11, 1898, p. 382), in speaking of Dr. Linde's 

 process, which is admitted to be substantially the same as mine. 

 Prof. Dewar said that "after some fourteen years' work he 

 ought to know something about low temperatures, but he must 

 confess that the practicability of such a mode of working had 

 never struck him." In illustrating the paper of December 

 1895, after showing an apparatus in which my process is em- 

 bodied, and which has since been manufactured and sold by a 

 firm of which his assistant, Mr. Lennox, is a member. Prof. 

 Dewar said in my hearing that the chief credit for persevering 

 with the development of that apparatus to a successful issue 

 was due to Mr. Lennox. In his account (published in your 

 issue of May 19) of the hydrogen apparatus, which also employs 

 my process, Prof. Dewar says that it was constructed by Mr. 

 Lennox's firm, and afterwards, in recognising "the invaluable 

 aid of Mr. Robert Lennox," says "it is not too much to say that 

 but for his engineering skill, manipulative ability, and loyal per- 

 severance, the present successful issue might have been indefinitely 

 delayed." I must allow that it is unfortunate for Prof. Dewar 

 that an assistant so very useful and helpful should have kept the 

 source of his inspiration on the vitally important features of the 

 new development from the knowledge of his chief, who, in dis- 

 cussing my paper of May 2 before the Society of Chemical 

 Industry, stated that he had been quite unaware of my com- 

 munication of plans and drawings to Mr. Lennox. He ought 

 however, when he did learn the facts, to have done me justice ; 

 whereas he says in his letter of the 9th inst. : " My assistant has 

 explained his position in the matter in letters addressed to 

 Engineer itig within the last few weeks." I earnestly hope that 

 all who care for the credit of science will read for themselves 

 the series of letters to Engineering hy " Arenel," Mr. Lennox, 

 and myself, from March 25 to May 13, in which it will be 

 difficult to find a satisfactory explanation of Mr. Lennox's 

 position. As I fear, however, that few people will exert them- 

 selves to look up these letters, I shall be pleased to send a copy 

 of the series to any one who writes for it to No. 20 Gower 

 Place, W.C. 



Prof. Dewar criticises my statement that I was the first in 

 this country to liquefy air and oxygen without employing other 

 refrigerants, on the ground that it had previously been done in 

 experiments at the Royal Institution. Now Mr. Lennox has 

 been given very great credit for the work in these experiments ; 

 and I do not admit that experiments by my method, developed 

 in collaboration with a gentleman to whom I had explained 

 the method embodied in them, and who had confessed that this 

 • method was a novelty to him, and had promised to help me to 

 the appliances required to work it, can be quoted as anticipa- 

 tions of my own work ; but to make my statement more correct 

 literally, I will say that my method (as compared with that of 

 Dr. Linde, which differs from it in details) was the first in this 

 country to liquefy air and oxygen without employing other 

 refrigerants. 



I may add that I mentioned my introduction to Mr. Lennox, 

 not as an "excuse" for calling on him, a course which 



NO. 1495, VOL. 58] 



obviously needs neither excuse nor justification — but to show 

 that I made my visit deliberately for a definite purpose, knowing 

 that I was in possession of an invention of great value for work, 

 such as he was practically engaged in. W. Hampson. 



June II. 



Dendritic Patterns caused by Evaporation. 



I HAVE been much interested in Miss Raisin's Royal Society 

 paper " On certain structures formed in the drying of a fluid 

 with particles in suspension," of which an account appears in 

 Nature for June 2. In connection with this subject it may be- 

 worth while placing on record the fact that the presence of 

 suspended particles is not essential for the production of dendritic 

 forms. 



Many years ago, when dabbling in microscopy, I mounted a 

 number of objects in glycerine jelly, and was much troubled by 

 the production of bubbles starting from the object and spreading, 

 in all directions, leaving a highly elaborate network of ramifi- 

 cations caused, no doubt, by the evaporation of water and 

 consequent shrinkage of the jelly. Having called attention to- 

 this defect in a box of slides circulated by the Postal Micro- 

 scopical Society, Mr. J. J. Wilkinson, of Skipton, very kindly 

 sent me the two accompanying photographs taken with magni- 

 fications of 25 and 50 diameters respectively. An additional 

 interest attaches to these from the fact that the slide from which 

 they were taken belonged to the collection of the late Mr. Tuffen 

 West. Needless to say, this slide was mounted for an entirely 



X25 



different object, and the specimen it contained was rendered 

 worthless by the subsequent formation of these beautiful but 

 troublesome vacuoles. It should be explained that it is the thin 

 branches which are formed of the remains of the jelly, the air 

 filling the broader species between them. G. H. Bryan. 



Bangor, June 10. 



Iridescent Surf at Cromer. 



Can any of your readers account for what seems to me to- 

 be a singular phenomenon, as, although familiar with the beauti- 

 ful sea-coast and clear green waves of many lands, I have never 

 seen anything of the sort elsewhere. 



The cliffs here, though fine when seen from a distance, are 

 only composed of sand and earth, large quantities of which have 

 been washed down by the recent rains, so that the sea is very 

 dirty, each turning wave being dark with mud. This mud has- 

 apparently some curious property, which causes a very moderate 

 surf to deposit long lines of foam all along the shore. Of this 

 foam (which is in no hurry to disperse) each bubble is brilliantly 

 iridescent, even on the dullest day of cold sea-fog, when there 

 is not one gleam of sunshine to produce prismatic effects. 



The inhabitants take this so entirely as a matter of course,, 

 that a lady whose attention I called to it, said that having 

 always seen it, .she had supposed it to be the natural condition- 

 of all sea-foam. 



Beautiful in themselves as are these myriad rainbows of the 

 shore, I am glad they are not universal, if they are only to be 

 seen as compensation for a discoloured sea ! 



It would be interesting to learn what is the ingredient in the 

 mud which, when combined with salt waves, produces such 

 tints. Constance F. Go'rdon Cummjng. 



Cromer, Norfolk, June ly. 



