( 630 ) 



It is liardly necessary to mention separately tliat tlie reaction of 

 the catalase can be made serviceable to the (listin,i>iiisliing of mother's 

 and cow's milk. 



Cow's milk which has been heated to 63° for half an honr no 

 longer possesses the property of decomposing H^ 0,, a property 

 which mother's milk still possesses in a rather considerable measnre 

 under the same circumstance. 



In a mother's milk which I thank to the kind interference of 

 Prof. KoüWER I found the following results, but it siiould be 

 observed that the action of the milk on the solution of hydrogen- 

 peroxide found place in the nitrometer of Lunge and that I read off 

 the volume of the developed oxygen after twelve hours : 



5 cM.' iBOther's milk not heated gave 24.8 cM.' oxygen. 



6 „ „ ,, heated to 63° for a 



quai'ter of an hour gave 18.5 ,, ,, 



5 „ „ „ „ 3 „ „ „ „ 7.5 „ 



5 ,, ,, ,, ,, for an hour „ 4.0 ,, „ 



Utrecht, December 1905. 



Physics. — "Some remarks on the quantity H in Boltzmann's 

 " Vorlesimgen liber Gastheorie"." By 0. Postma. (Communi- 

 cated by Prof. H. A. Lorentz). 



(Communicated in the meeting of December 30, 1905). 



§ 1. It seems to me that some of the views advanced in one of 

 the first paragi'aphs of the above mentioned work, are inaccurate; 

 and it may be desirable to draw attention to this fact, because 

 several considerations of Boi.tzmann and others are based on them. 

 1 mean § 6 on the "Mathematische Bedeutung der Grosse H". 



Ill the case of a gas the molecules of which are all of the same 



type, this quantity is represented by if.l/.dia. Now, in § 5, assum- 

 ing that the gas is of the simplest nature and that the motion of 

 the molecules is "molecular-ungeordnet", Boltzmann has shown that, 

 in general, the quantity H decreases by the collisions and is minimum 

 in the stationary state. 



Such a gas would therefore move of its own accord to the 

 stationary state i. e. with IMaxwell's distrilmtion of velocities, as 

 Boltzmann shows further on. 



Now it is demonstrated in § 6 that the quantity H has also 



