I 617 ) 
complex tellurohydrogen sulphides. The investigation of this exceedingly 
complicated subject is being continued in the direction indicated. 
§ 12. Summarizing the results of these investigations, I believe I 
may say: 
1. That the elements tellurium and sulphur do not form compounds, 
but mixed crystals. 
2. That the elements tellurium, selenium and sulphur behave in 
quite an analogous manner towards the sulphides of the alkali and 
alkali-earth metals, and cause the formation of complex sulpho-, 
seleno- or tellurohydrogen sulphides of a different type, and that it 
is quite unnecessary to presuppose the intermediate formation of 
selenium-sulphur or tellurium-sulphur compounds. 
3. That the position, given by Dumas, to tellurium in the sulphur 
group as the first homologue of selenium is quite justified so far as 
the mutual behaviour of these elements is concerned, and that sulphur, 
selenium, and tellurium form a natural triad of elements, which are 
more adjacent to each other than any one of them is to oxygen. 
Groningen, Inorg. Chem. Lab. of the University. 
Physics. — “Some remarks on Prof. Kohnstamm’s reply.” By Dr. 
J. J. van Laar. Communicated by Prof. Lorentz. 
In these Proceedings of Jan. 6 th 1910 Prof. Kohnstamm has inserted 
a reply to my remarks suggested by a paper by Messrs. Timmermans 
and Kohnstamm. Though I, too, very reluctantly continue the discus¬ 
sion, I feel obliged to briefly revert to this matter for the last time, 
in order to prevent further misunderstanding. 
So I will just point out that Mr. Kohnstamm is quite silent about 
the cardinal point of my remarks, given in point a second part, 
point e and point /; viz. that Messrs. T. and K. in consequence of 
their disregard of the last five of my seven papers on the subject 
in question have wrongly asserted that the “abnormal” type III could 
not occur for normal substances, and that this would be due to my 
restricting supposition a lt = Vafa ,. Only to remove this misunder¬ 
standing — as I had asserted the very opposite of this I wrote 
my preceding paper. 
