354 



NA TURE 



[August io, 1905 



a gain of cooling by letting liquid air vaporise at a lower 

 temperature than that at which it had condensed, taking 

 up more latent heat at the lower temperature than it had 

 given out at the higher ; and he overlooked the fact that 

 the difference would be balanced by the specific heat given 

 out by the liquid while being cooled to the lower tempera- 

 ture ! Under a fresh patent in England Pictet has now 

 for some years been associated with powerful supporters in 

 installing a large and costly plant at Manchester with the 

 same object. None of the former fallacies appear in the 

 new patent. Whether practical success will attend the 

 effort remains to be seen. 



The liquid oxygen, or air rich in oxygen, obtained by 

 distillation from liquid air, if mixed with a good com- 

 bustible, such as cotton wool, makes an e.xplosive. The 

 Austrian military authorities, and the engineers engaged 

 in tunnelling under the Alps, both made long and careful 

 trials of such explosives ; but the inevitable arrangements 

 were too cumbrous, and the results too uncertain. 



The nearest attempt to make what is called a practical 

 use of liquid air is that of Dr. Allan .Macfadyen (see 

 Nature, June i8, 1903, p. 152, and October 22, 1903, 

 p. bo8). By freezing the bacilli of typhoid in liquid air 

 he makes them brittle enough for trituration in a mortar. 

 By centrifugalisation the intracellular poison can then be 

 separated from more fibrous material, and then by the 

 methods of Pasteur an anti-typhoid serum prepared which 

 promises to be of real value. 



The most pronounced successes of liquid air have been 

 in connection with scientific research. It was with liquid 

 air made by the self-intensive process with a Hampson 

 machine that Sir William Ramsay discovered krypton, 

 xenon, and neon, that Prof. Rutherford and Mr. Soddy 

 proved the emanations of radium and thorium to be con- 

 densable and vaporisable, that Ramsav proved the evolu- 

 tion of helium from radium emanations, and many other 

 important investigations were carried out. Finally, it was 

 by an extension of the same process that hydrogen was 

 liquefied. 



THE MEETIXG OF THE BRITISH 

 MEDICAL ASSOCIATIOW 



A NUMBER of valuable and instructive papers were 

 ■^ contributed at the recent meeting of the British 

 ' Medical Association at Leicester, but the majority were 

 technical and of a medical nature. The following, in 

 addition to those described last week (p. 330), are, how- 

 ever, of more general interest : — 



In the section of medicine. Dr. Nathan Raw (Liverpool) 

 read a paper on human and bovine tuberculosis, with 

 special reference to bovine infection in children. He 

 said that while agreeing with the German view that there 

 were decided differences between the bovine and human 

 tubercle bacilli, he believed that bovine tuberculosis was 

 a danger to human beings. 



Bovine tuberculosis affected young people, was traceable 

 to infected milk, and infected the tonsils, the alimentary 

 tract, the glands, and, through the blood, the meninges, 

 the bones, the joints, and other parts, while human 

 tuberculosis was air-borne, and infected adults bv wav of 

 the lungs as pulmonary phthisis. In evidence of this Dr. 

 Raw indicated the rarity of pulmonary phthisis in infants 

 and children, and, on the other hand, the comparative 

 rarity of other than pulmonary lesions in adults, and 

 suggested, further, that early tuberculous disease, presum- 

 ably bovine, appeared to be protective against phthisis, 

 as the development of pulmonary tubercle was relatively 

 rare in those of a strumous diathesis who had suffered in 

 infancy from bone and gland lesions. 



In conclusion. Dr. Raw alluded to the frequency of 

 tuberculosis among cattle, and the importance of the in- 

 spection of cattle and dairies. 



Dr. F. J. Poynton (London) gave the results of his 

 experience of milk to which sodium citrate had been added 

 in the feeding of infants. The addition of sodium citrate 

 to milk results in the formation of calcium citrate, and 

 milk so treated forms a much finer curd and is more 

 digestible than untreated milk. The sodium citrate may 



NO. 1867, VOL. 72] 



be added to the amount of i to 2 grains to the fluid ounce 

 of milk. 



In the section of ophthalmology. Prof. Hess (Wiirzburg) 

 demonstrated by a series of beautiful drawings the influence 

 of light in causing a migration of pigment in the retina 

 of cephalopods. He had found in these eyes visual purple 

 which had hitherto not been detected in any invertebrate. 



.-\11 cephalopods studied by him showed this pigmentary 

 migration within the retina, but the rapidity of the migra- 

 tion differed in various species, and it was different in 

 different parts of the same retina, especially in the small 

 horizontal stripe which contained very long and small rods, 

 and corresponded evidently to an area of maximum vision. 



In the section of tropical medicine, Mr. R. Newstead, 

 of the Liverpool School of Tropical Medicine, read a 

 paper on ticks concerned in the dissemination of disease 

 in man, and gave a description of the Oriiithodorus 

 mouhata which conveys tick fever, a spirillar infection, in 

 the Congo Free State. 



Mr. Newstead had found that in many respects the 

 habits of the Oruithodorus woubata were not unlike those 

 of Argas pcrsiciis, but the inert character of the larva of 

 Ornithodorus inoiihata was unique among the Ixodina^, in 

 that it passes the whole of its life within the egg. The 

 female Ornithodorits moithata laid eggs which were 

 hatched, not as larvic, but as nymphre, although on the 

 ninth day the larva was fully formed and the egg shell 

 split, but the voung tick remained until the fifteenth day, 

 when as a nymph it escaped simultaneously from its larva 

 covering and egg shell. 



Dr. (iraham (.Sierra Leone) contributed a paper on 

 guinea w-orm and its hosts. He had found that the in- 

 cidence of the disease corresponded with the incidence of 

 a Cyclops, the presumed intermediate host, both seasonally 

 and as regards its maximum manifestation. 



SOME ASPECTS OF MODERN WEATHER 

 FORECASTING.' 



A FTER referring to the circumstances in which he 

 was called upon to deliver the evening discourse in 

 the absence of the Dean of Westminster, the lecturer 

 explained that he had chosen the subject, not because he 

 regarded weather forecasting as the only, or, from the 

 scientific point of view, the most important practical 

 branch of meteorology, but because, in a general sense, 

 the possibility of its application to forecasting — the deduc- 

 tion of effects from given causes — was the touchstone of 

 scientific knowledge. 



The process of modern forecasting was illustrated by 

 the daily weather charts of the period from February i, 

 1904, up to the evening of February 12, which exhibited 

 the passage over the British Isles of a remarkable sequence 

 of cyclonic depressions, reaching a climax in a very deep 

 and stormy one on the evening of the lecture. It w"as thus 

 pointed out that the barometric distribution and its changes 

 were the key to the situation as regards the weather, and 

 this was supported by exhibiting the sequence of weather 

 accompanying recognised tvpes of barometric changes, as 

 shown in the self-recording instruments at the observ- 

 atories in connection w'ith the Meteorological Office. 



Some cases of difficulty in the quantitative association of 

 rainfall or temperature changes with barometric variations 

 were then illustrated. The barometric distributions in the 

 weather maps for .^pril 8 and .April 16, 1903, were shown 

 to be almost identical, and yet the w-eather on the later 

 date was 10° colder than on the earlier. The observatory 

 records for June 22, 1900, showed that a barometric dis- 

 turbance of about the fiftieth of an inch, too small to be 

 noticed on the scale of the daily charts, passed across the 

 country from Valencia to Kew, over Falmouth, in about 

 twenty-four hours, and produced at each observatory 

 characteristic changes of temperature and wind, and also 

 in each case about a fifth of an inch of rainfall. 



Some examples of the irregularity of motion of the 

 centres of depressions were also given, including one which 

 travelled up the western coasts of the British Isles on 

 October 14 and 15, and down the eastern coasts on 



1 Abstract of a discourse delivered at ihe Royal Inslilulion of Great 

 Britain by Dr W. N. Shaw, F.R.S. 



