Chemistry and Physics. 73 



angles to the lines of force between the condenser plates. The 

 author gives the simple theory and examples of the working of 

 the new instrument. — Ann. der Physik und Chemie, No. 4, 1893, 

 pp. 592-605, pp. 726-733. J. T. 



12. Magnetic Properties of Liquid Oxygen. — At a discourse 

 delivered before the Royal Institution, Professor Dewar exhibited 

 a pint of liquid oxygen. The temperature of the liquid oxygen 

 at atmospheric pressure was 180° C. Reference was made to a 

 remarkable experimental corroboration of Lord Kelvin and Pro- 

 fessor Tait's thermo-electric diagram for low temperatures. If 

 lines of copper and platinum were prolonged in the direction of 

 negative temperature they should intersect at —95° C. Similarly 

 copper and palladium lines would cut one another at — 170° C. If 

 the diagram is correct the E. M. F. of the thermo-electric junction 

 of these pairs of metals should reverse at these points. A Cu-Pt 

 junction connected to a reflecting galvanometer was placed in 

 oxygen vapor and cooled down. At —100° C. the spot of light 

 stopped and reversed. A Cu-Pd junction placed in a tube con- 

 taining liquid oxygen gave a reversal at — 170° C. Liquid oxygen 

 is a non-conductor of electricity. A spark taken from an induction 

 coil one millimeter long in the liquid requires a potential equal to 

 a striking distance in air of 25 mm . Thus oxygen is a high insu- 

 lator. The magnetic moment of liquid oxygen is about 1000, 

 when the magnetic moment of iron is taken as 1,000,000. Be- 

 tween the poles of the magnet all the liquefied air went to the 

 poles, there was no separation of the oxygen and nitrogen. 

 Liquid air has the same high insulating power as liquid oxygen. 

 At —200° C. the molecules of oxygen had only one-half of their 

 ordinary velocity, and had lost three-fourths of their energy. 

 Liquid oxygen had no action upon a piece of phosphorus and 

 potassium or. sodium dropped into it. A photographic plate 

 placed in liquid oxygen could be acted upon by radiant energy 

 and at a temperature of -—200° C. was still sensitive to light. 

 Professor M'Kendrick had tried the effect of low temperatures 

 upon the spores of microbic organisms by submitting in sealed 

 glass tubes blood, milk, flesh, and similiar substances for one hour 

 at a temperature of — 182° C. and subsequently to a temperature 

 of blood heat. The tubes on being opened were all putrid. Seeds 

 also withstood a similar amount of cold. These experiments 

 proved the possibility of Lord Kelvin's suggestion that life may 

 have been brought to the newly cooled earth upon a seed-bearing 

 meteorite.— Nature, May 25, 1893, pp. 89-91. J. t. ' 



13. Specific Heat of Liquid Ammonia.— ~ Dr. Hans von Strom- 

 beck has called the attention of the editors to the paper by him- 

 self in volume cxxx of the Journal of the Franklin Institute (Dec. 

 1890, p. 467) in which he gives a detailed account of his deter- 

 mination of the specific heat of liquid ammonia. The mean 

 result obtained was 1 '22876. This result should properly have 

 been referred to in the paper upon the same subject published in 

 our March number of this year, page 200. 



