(76) 



Formerly the escape of the gas which transfers the pressure on 

 the mercury with the above mentioned consequences was to be feared 

 at the connecting pieces of the steel capillaries q with the cocks K 

 and the "["-pieces T (cf. fig. 1, Comra. W 44). This was especially 

 dangerous as the place where it happened was often detected too 

 late. As packing between the flat steel surfaces of the joints for 

 cocks, flanged tubes, and "["-pieces, we use now only a single sheet 

 of parchment paper. Leaks rarely occur. Moreover in the new arrange- 

 ment care is taken that each place where gas might escape is kept 

 under vaselin oil, so that even the smallest leak betrays itself immedia- 

 tely by a gasbulb raising in the oil. 



In order to attain this the mounting of T and K is modified as 

 shown on the annexed plate. Fig. 2 is a part taken from the 

 plate of Comm. W. 44 (front elevation). Fig. 3 is a top view of this 

 part from a section ??. Figs. 4, 5 and 6 next to it show the present 

 arrangement in front elevation, section, and top view. The diawings 

 do not rec{uire much explanation. Hu is a wooden case (tinlined and 

 protected from action of mercuiy by parchment paper), in which are 

 placed the lube H (vide Ccn m. N". 44) with all the cocks K and 

 the "P-picces 2' connected with it. {K^^ is a loose key on the cock- 

 needle, Hk is a tap; the contents of the case is about 0.8 hectoliter). 



II. Iniprovement in the transference of pressure hy compressed 

 gas especlaUij for the determination of isothermals. 



The advantages of the transference of pressure from the experi- 

 mental apparatus to the measuring apparatus by means of compressed 

 gas caused this method to be repeatedly used for experiments at 

 Leiden. The drawback of it is, howe\'er, that much care is required 

 to make connections which are perfectly tight and that it is a very 

 elaborate work to seek for leaks, especially wdien there are a great 

 number of connections. It may happen that a whole series of experi- 

 ments loses its value when the existence of a leak is not immediately 

 detected. For some time, therefore, we have arranged those coimec- 

 tions where the escape of gas is to be feared, (as explained in part I 

 of this paper for the open manometer) so that they can be covered 

 with vaselin oil and yet are easily reached. It has appeared that 

 with the arrangements based upon this principle we can work so 

 much more securely and rapidly that it more than balances the 

 small complication which sometimes arises when we carry out 

 the principle. 



As an elucidation we have represented in fig. 7 of the annexed 



