Mr. H. Giraud on Ter iodide of Chromium, 321 



The results of two sets of experiments were as follows : 



Interval. Time. 



Change. Multiple of Mean of two 



tt-bWtt inch. Experiments. 

 From maximum "^ , 



of 1st order [> 6 11*5 



to max. of 4th 

 2nd 



to 4th 



3rd 



} 

 } 

 } 



7-5 

 3-5 



to 4th 



From minimum 1 



of 1st order > 6 8'5 



to min. of 4th 

 2nd 



to 4th 



3rd 



4-75 



to 4th 



In all such experiments the most troublesome part consists 

 in having to wait in each instance until the apparatus has 

 cooled down to the same temperature, before commencing. 

 This and numerous other precautions are not here dwelt 

 upon, as they will soon suggest themselves to those who may 

 be induced to enter upon such experiments. 



XLIX. On the Nature and Properties of Teriodide of Chro- 

 mium. By Mr. Herbert Giraud, F.B.S.E,, Mem. Med. 

 Soc, Edin. 



To the Editors of the Philosophical Magazine and Journal, 



Gentlemen, 



A LT HOUGH the remarkable and beautiful combinations 

 '^ of chromium with chlorine and fluorine are well known 

 to every chemist, yet I am not aware that any iodide of 

 chromium has hitherto been formed; therefore a short ac- 

 count of one which I have recently produced may not be un- 

 interesting. 



When we consider the relative electro-chemical condition 

 of iodine compared with that of chlorine or fluorine, we are 

 led to conclude that if any combination can be effected be- 

 tween chromium and iodine, such a combination would be 

 held together by weaker affinities than those which are exerted 

 in the analogous compounds of chromium with chlorine or 

 fluorine ; accordingly we find that the compound we are about 

 to describe is subject to decomposition from slight causes. Th^ 

 Phil. Mag. S.3. Vol. 12. No. 75. April 1838. 2 H 



