(5 



Messrs. Lecher and Per: 



iter 



on the Absorption 















Deflec- 









Name and 

 Pressure 



of gas. 



R 



Keversal-points. 



E x 



tion in 

 divi- 

 sions 

 of the 



Mean. 



J. 











Pv 



Pr 



Pr 



Vv 



022-8 

 6249 

 621-6 



scale. 



556-8 

 558-9 

 555-6 



1 557-1 



10008 



6 



Fure air at 



atmospheric 



pressure. 



66 



66 

 66 



603 

 675 



682 



543 



538 

 534 



000 

 000 

 004 



008 

 008 

 003 



II 



Vacuum. 



66 



67 



07 



650 

 652 

 657 



540 

 541 



538 



058 

 002 

 002 



011 

 010 

 010 



622-3 

 624-1 

 623-6 



556-3 

 557-1 

 556-6 



1 556-7 



10000 



05 



Pure air at 



atmospheric 



pressure. 



65 



66 



68 



682 

 684 

 677 



531 

 531 

 534 



655 

 654 

 663 



005 

 015 

 011 



6172 

 619-5 

 6237 



552-2 



553 55 



555-7 



1 553-8 



99-49 



►** 



Vacuum. 



66 

 66 

 64 



648 

 647 

 647 



537 

 538 

 535 



656 

 655 

 653 



609 

 609 

 608 



620-1 

 0190 

 017-9 



5541 



5536 

 553-9 



1 553-9 



99-50 

 10014 



CO 



Pure air at 



atmospheric 



pressure. 



65 

 65 

 66 



674 

 682 

 690 



542 

 543 

 530 



648 

 654 

 655 



612 

 603 

 002 



010-6 

 018-0 

 6161 



551-1 

 553-1 

 550-1 



1 551-3 



II 



Vacuum. 



66 

 65 

 64 



661 



659 



658 



544 



539 

 537 



650 

 650 

 048 



605 



003 

 002 



6170 

 615-5 

 6139 



551-0 

 550-5 

 549-9 



1 550-5 



10000 



ci 



Pure air at 



atmospheric 



pressure. 



63 

 64 

 66 



670 

 670 



088 



538 

 538 

 532 



645 



048 

 050 



590 

 000 

 601 



610-5 

 013-3 

 013-0 



547-5 

 549-3 

 547-6 



I 548-1 



99-56 



II 



Vacuum. 



05 

 65 

 64 



000 

 601 

 058 



540 

 539 

 535 



050 

 051 

 651 



603 

 604 

 600 



615-6 

 616-3 

 613-3 



550-6 

 551-3 

 549-3 



I 550-4 



99-90 



We found that in course of time the deflections on our 

 galvanometer became continually smaller, partly because the 

 needles became less nearly astatic, but chiefly because the 

 points of contact at the ends of the conducting-wires became 

 oxidized in spite of the careful varnishing which they had 

 received, and thus the resistance was increased. 



These changes were of course imperceptible during any 

 one series of experiments ; but they explain the differences 

 observable in the deflections of two series of experiments, 

 which may be printed the one under the other, though pos- 

 sibly there may have been actually an interval of some months 

 between them. 



As far as the Table given above is concerned, it clearly appears 

 that the; absorption of heat-rays from a source at 100° C. by a layer 

 of 31 centimetres thickness, is so small that it cannot be mea- 

 sured; for if we take the mean of the first three experiments and 



