( 1012 ) 
4. The substance originating in the intestinal mucous membrane, 
which brings about this action, is not destroyed by being boiled, and 
is in all probability no calcium. 
5. Besides a substance which, as we know, possesses the faculty 
of being able to activate trypsinogen, which substance is rendered 
inactive by being boiled, the intestinal mucous membrane contains, 
therefore, also another substance which has the power of stimulating 
active trypsin, a substance which is not rendered inactive by being 
boiled. 
Groningen, January 22°¢ 1911. Physiological Laboratory. 
Physics. — “/sotherms of monatomic substances and of their binary 
miatures. LN. The behaviour of argon with regard to the law 
of corresponding states.” By Prof. H. Kamertinen OnNes and 
CG. A. CROMMELIN. Comm. N°. 120« from the Physical Laboratory 
at Leiden. 
(Communicated in the meeting of February 25, 1911). 
§ 1. The mean reduced surface of state for monatomic substances. 
A diffieulty which is by no means small is introduced into theoretical 
investigations dealing with the equation of state by the fact that, 
for every substance, and, in particular, for substances of simple 
molecular construction, the region that has been experimentally 
investigated extends over a small range of reduced pressure and of 
reduced temperature. If the law of corresponding states were strictly 
obeyed, this diffieulty could be obviated by reducing and then com- 
bining with each other the regions investigated for the various 
substances. In this way the mean reduced equation of state has been 
synthesized: in the form VII. 1 *). It has been obtained from AmaGat’s 
observations on hydrogen, oxygen, and nitrogen, YouNG’s on isopentane 
and Amacat’s and Ramsay and Youne’s on ether. In this way the 
equation of state has been obtained for an imaginary substance which, 
if further amplified by the disturbance function *) for the neighbourhood 
of the critical point, is suitable for all calculations in which the 
validity of the law of corresponding states is assumed. And this 
equation is of particular use in tracing deviations from the law of 
corresponding states, for it affords a suitable means of easily comparing 
1) Suppl. NO. 19 (May 1908). 
2) Proc. Febr. 1908. Comm. N°. 104. 
