630 



SCIENCE. 



[N. S. Vol. XVI. No. 407. 



rarily increased by cooling in liqtiid air,, 

 but the increase seems to have reached a 

 limit, because on further cooling to the 

 temperature of liquid hydrogen hardly any 

 further change was observed. The study 

 of the thermo-electric relations of the met- 

 als at low temperatures resulted in a great 

 extension of the well-laiown Tait thermo- 

 electric diagram. Tait found that the 

 thermo-electric power of the metals could 

 be expressed by a linear function of the 

 absolute temperature, but at the extreme 

 range of temperature now under considera- 

 tion this law was found not to hold gen- 

 erally ; and further, it appeared that many 

 abrupt electric changes take place, which 

 originate probably from specific molecular 

 changes occurring in the metal. The 

 thermo-electric neutral points of certain 

 metals, such as lead and gold, which are 

 located about or below the boiling-point of 

 hydrogen, have been found to be a conven- 

 ient means of defining specific tempera- 

 tures in this exceptional part of the scale. 

 The effect of cold upon the life of living 

 organisms is a matter of great intrinsic in- 

 terest, as well as of wide theoretical im- 

 portance. Experiment indicates that mod- 

 erately high temperatures are much more 

 fatal, at least to the lower forms of life, 

 than are exceedingly low ones. Professor 

 McKendrick froze for an hour at a tem- 

 perature of 182° C. samples of meat, milk, 

 etc., in sealed tubes; when these were 

 opened after being kept at blood heat for 

 a few days, their contents were found to be 

 quite putrid. More recently some more 

 elaborate tests were carried out at the Jen- 

 ner Institute of Preventive Medicine on a 

 series of typical bacteria. These were ex- 

 posed to the temperature of liquid air for 

 twenty hours, but their vitality was not 

 affected, their functional activities re- 

 mained unimpaired, and the cultures which 

 they yielded were normal in every respect. 



The same resvilt was obtained when liquid 

 hydrogen was substituted for air. A sim- 

 ilar persistence of life in seeds has been 

 demonstrated even at the lowest tempera- 

 tures ; they were frozen for over a hundred 

 hours in liquid air, at the instance of 

 ]\Iessrs. Brown and Escombe, with no other 

 result than to affect their protoplasm with 

 a certain inertness, from which it recovered 

 with warmth. Subsequently commercial 

 samples of barley, pea, vegetable marrow, 

 and mustard seeds were literally steeped 

 for six hours in liquid hydrogen at the 

 Royal Institution, yet when they were sown 

 by Sir W. T. Thiselton Dyer at Kew in the 

 ordinary way, the proportion in which ger- 

 mination occurred was no less than in the 

 other batches of the same seeds which had 

 suffered no abnormal treatment. Bacteria 

 are minute vegetable cells, the standard of 

 measurement for which is the 'mikron. ' 

 Yet it has been found possible to completely 

 triturate these microscopic cells, when the 

 operation is carried out at the temperature 

 of liquid air, the cells then being frozen 

 into hard breakable masses. The tyjjhoid 

 organism has been treated in this way, and 

 the cell plasma obtained for the purpose 

 of studying its toxic and immunizing prop- 

 erties. It would hardly have been antici- 

 pated that liquid air should find such im- 

 mediate application in biological research. 

 A research by Professor Macfadyen, just 

 concluded, has shown that many varieties 

 of microorganisms can be exposed to the 

 temperature of liquid air for a period of 

 six months without any appreciable loss of 

 vitality, although at such a temperature the 

 ordinary chemical processes of the cell 

 must cease. At such a temperature 

 the cells cannot be said to be either 

 alive or dead, in the ordinary ac- 

 ceptation of these words. It is a 

 new and hitherto unobtained condition 

 of living matter— a third state. A final in- 



