1187 
action of potassium hydrogen sulphate as well as of phthalic anhy- 
dride, which, judging from provisional experiments consists of hexatriene. 
In consequence of the fact noticed by Dr. C. J. EnkLaar (loc. cit.) 
that the homologue of hexatriene which he prepared can be obtained 
in a crystalline condition by strong cooling, Mr. Mutu has cooled 
a freshly prepared and carefully fractioned specimen of hexatriene in 
a mixture of solid carbon dioxide and alcohol and obtained it also 
in the erystalline form *), so that this fact may be utilised for the 
purification of this hydrocarbon. 
Finally it may be mentioned here that Mr. Le Huvux, by reduction 
of the chloroacetine of s. divinylglyeol with a copper-zine couple in 
ethereal solution with addition of hydrochloric acid, obtained a liquid 
boiling at 77°—81° which on strong cooling became crystalline and 
consists very probably of hexatriene 1, 8, 5. At any rate it yields 
with bromine a dibromide identical with the dibromide from the 
said hydrocarbon. 
Utrecht. Org. Chem. Lab. Univ. 
Physics. — “On Kinstein’s theory of the stationary gravitation field.” 
By Prof. P. Exrenrest. (Communicated by Prof. H. A. Lorentz). 
(Communicated in the meeting of Febr. 22, 1913). 
§ 1. Let a “laboratory” £ with the observers in it have some 
accelerated motion with regard to a system of coordinates 2, y, 2, 
which is not accelerated. Let it e.g. move parallel to the z-axis with 
some positive acceleration or other. Then the observers will find that 
all the inert masses which are at rest with regard to the laboratory, 
exert a pressure on the bodies which are in contact with their bottom 
side. There are two ways for these observers to explain this pressure : 
a. “Our laboratory has an acceleration upwards, hence all inert 
masses press on the bodies under them.” 6. “Our laboratory is at 
rest. A field of force acts in it, which pulls the masses down.” 
Observations on the course of the rays of light seem to make it 
possible to decide experimentally between the suppositions a and 0: 
with regard to the system of coordinates w,y,z the light travels 
rectilinearly. Hence with regard to an accelerated laboratory curvi- 
linearly. By means of this curvilinear propagation of the rays of 
light the observers might therefore ascertain that their laboratory 
has an accelerated motion. 
1) Preparations which have been kept for some time and then contain polyme- 
rides do not solidify even at this low temperature. 
J 
