462 



Mr. J. C. W. Hunifrey. 



[May 28, 



8 per cent., the smaller figure in this case being accounted for pro- 

 bably by the more sluggish metabolism in this animal. 



These results regarding the carbonic acid excretion are confirmed 

 by those of water excreted and oxygen absorbed. For these two bodies 

 the figures are by no means so constant as for the carbonic acid, the 

 reason for this being no doubt that the technique for the estimation 

 of them is much more complicated, and the chance of experimental 

 error so much greater. The results have been further confirmed by 

 observing the rectal temperature during the various periods. It will be 

 noticed that even in an atmosphere of air a distinct fall is recorded 

 after the animal has been in the chamber for about an hour. This 

 fall is, however, more marked when the animal is placed in oxygen, 

 and it again rises somewhat when the oxygen is replaced by air. 



Besides the experiments here recorded, we have performed a con- 

 siderable number in which the carbonic acid and water excretions 

 alone were recorded, and in every case we have obtained the above 

 result. Two of the most typical of these tables are given here as 

 examples (see Experiments 4 and 5). 



This research has been carried out with the help of a grant from the 

 Government Grant Fund of the Eoyal Society. 



"Effects of Strain on the Crystalline Structure of Lead." By 

 J. C. W. Humfeey, B.Sc. (Vict.), 1851 Exhibition Research 

 Scholar (University College, Liverpool), St. John's College, 

 Cambridge. Communicated by Professor Ewing, F.E.S. Re- 

 ceived May 28 —Bead June 5, 1902. 



(Abstract.) 



The paper describes experiments carried out in the Engineering 

 Laboratory at Cambridge, under Professor Ewing. The material used 

 was a pure variety of lead which crystallised on a particularly large 

 scale. Test pieces were obtained from it in which the part under 

 observation (which extended right across the centre of the specimen as 

 well as through from front to back) was a single crystal uniformly 

 oriented throughout, and the paper deals with the behaviour of such 

 uniformly oriented parts under the influence of strain. It was found 

 that by suitable etching a very beautiful system of geometrical pits 

 (which took the form of negative cubo-octahedra) could be produced 

 on the surface of the specimen, and by means of these any change of 

 orientation could be readily observed. 



In the first experiments described the specimens were strained in 



