304 PROCEEDINGS. 



The three colours in equal proportions give grey, i.e., 1° red, 1° 

 blue, 1° yellow. Now 1° red + 1° blue produce purple, 1° blue 

 + 1° yellow produce green, 1° red + 1° yellow produce orange. 

 For pure white as a back ground snow was taken as the standard, 

 and it was found that pure plaster of Paris is 0*12° greyer than 

 snow and Chance's opal glass faintly more grey. The observation 

 is made with one eye only, as hundreds of trials showed that in 

 but few cases was the colour perception the same with both eyes. 



In case of any change taking place in the colour of the standard 

 glasses there are various solutions by which the standard can be 

 recovered as for example a column of distilled water for blue. 



These instruments are now largely coming into use for colour 

 determinations in malt, beer, wine, oils, dyes, and for the colouri- 

 metric determination of carbon in steel and ammonia in water. 

 In the latter and some others, as flour, specially coloured glasses 

 are used which give the reading directly, using one tint only. 



WEDNESDAY JULY 1, 189 J. 



H. C. Russell, b.a., c.m.g., p.r.s., President, in the Chair. 



Thirty-five members and five visitors were present. 



The minutes of the preceding meeting were read and confirmed. 



The certificates of eighteen new candidates were read for the 

 third time, of four for the second time, and of four for the first 

 time. 



The following gentlemen were duly elected ordinary members 

 of the Society : — 



Bowman, Archer S., c.E. ; Sydney. 

 Campbell, John Honey ford ; Sydney. 

 Chisholm, James Kinghorn, j.p.; Narellan. 

 Clarke, Gaius, c.E. ; North Sydney. 

 Dunstan, Benjamin ; Sydney. 

 Gill, Robert J., c.E.; Blayney. 

 Guthrie, F. B. ; Sydney. 

 Halliday, The Hon. William, m.l.c. ; Sydney. 



