ON THE PRODUCTION OF HALOIDS FROM PURE MATERIALS. 347 
The Production of Haloids from Pure Materials —Interim Report of a 
Committee, consisting of Professor H. E. ARMstronG, Professor W. 
R. Dunstan, Mr. C. H. BoTHaMuey, and Mr. W. A. SHENSTONE 
(Secretary). (Drawn up by the Secretary.) 
CONSIDERABLE progress has been made with the work of this Committee 
during the past year. The difficulties mentioned in past reports having 
at length been overcome, a number of experiments are in hand which will 
it is believed be completed early in 1897. Meanwhile some of the material 
prepared has been made useful for some subsidiary investigations which 
also are approaching completion. No further grant is at present necessary. 
But it is recommended that the Committee be reappointed. 
The Action of Light upon Dyed Colowrs.—Report of Convmittee, 
consisting of Professor T. E. THoRPE (Chairman), Professor J. J. 
HumMEL (Secretary), Dr. W. H. Perkin, Professor W. J. RussELL, 
Captain ABNEY, Professor W. Stroup, and Professor R. MELDOLA. 
(Drawn up by the Secretary.) 
Durine the past year (1895-96) the work of this Committee has been 
continued, and a large number of wool and silk patterns, dyed with 
various natural and artificial blwe and green colouring matters, have 
been examined with respect to their power of resisting the fading action 
of light. 
The general method of preparing the dyed patterns, and the manner 
of exposing them under glass, with free access of air and moisture, were 
the same as already adopted in previous years. 
The thanks of the Committee are again due to James A. Hirst, Esq., 
in whose grounds the patterns were exposed at Adel, near Leeds. 
Each dyed pattern was divided into six pieces, one of which was 
protected from the action of light, while the others were exposed for 
different periods of time. These ‘ periods of exposure’ were made equivalent 
to those adopted in previous years by exposing, along with the patterns, 
special series of ‘standards,’ dyed with the same colouring matters as were 
then selected for this purpose. The standards were allowed to fade to the 
same extent as those which marked off the ‘ fading period’ in previous years, 
before being renewed or before removing a set of dyed patterns from the 
action of light. The patterns exposed during the past year are therefore 
comparable, in respect of the amount of fading action to which they have 
been submitted, with the dyes already reported upon. 
The patterns were all put out for exposure on July 19, 1895, cer- 
tain sets being subsequently removed on the following dates :—August 12, 
September 3, September 20, 1895 ; April 1, July 9, 1896. Of these five 
‘periods of exposure’ thus marked off, periods 1, 2, 3 were equivalent to 
each other in fading power, whereas periods 4 and 5 were each equivalent 
to four of the first period in this respect ; hence five patterns of each 
colour have been submitted respectively to an amount of fading equal 
to 1, 2, 3, 7, and 11 times that of the first ‘fading period’ selected—viz., 
July 19 to August 12, 1895. 
The dyed and faded patterns have been entered in pattern-card books 
in such a manner that they can be readily compared with each other. 
