March 1, 1878.] 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
GSD 
"white by their mixture. The mixture of blue and yellow 
pigments undoubtedly produces green, but the mixture 
of pigments is totally different from the mixture of 
lights. Helmholtz has revealed the cause of the green 
in the case of the pigments. No natural colour is pure. 
A blue liquid, or a blue powder permits not only 
the blue to pass through it but a portion of the adjacent 
green. A yellow powder is transparent not only to the 
yellow light but also in part transparent to the adjacent 
green. Now when blue and yellow are mixed together 
the blue cuts off the yellow, the orange, and the red; the 
yellow, on the other hand, cuts off the violet, the indigo, 
and the blue. Green is the only colour to which both 
are transparent, and the consequence is that when light 
falls upon a mixture of yellow and blue powders, the 
green alone is sent back to the eye. The explanation of 
the mixture of pigments will be subjected to the test of 
experiment; and in a subsequent lecture the mixture of 
coloured lights will be employed to prove that blue and 
yellow, by their blending, produce white. This question 
of absorption is one of the most subtle and difficult in 
molecular physics. We are not yet in a condition to 
grapple with it, but we shall be by-and-by. 
Meanwhile we may probably glance back on the web 
of relations which these experiments reveal to us. AVe 
have in the first place in solar light an agent of exceed¬ 
ing complexity, composed of innumerable constituents 
refrangible in different degrees. We find, secondly, the 
atoms and molecules of bodies gifted with the power of 
sifting solar light in the most various ways, and produc¬ 
ing by this sifting the colours observed in nature and art. 
To do this they must possess a molecular struction com¬ 
mensurate in complexity with that of light itself. 
Thirdly, we have the human eye and brain so organized 
as to be able to take in and distinguish the multitude of 
impressions thus generated. Thus the light at starting 
is complex, to sift and select it as they do natural bodies 
must be complex. Finally, to take in the impressions thus 
generated the human eye and brain must be highly com¬ 
plex. If we were permitted to inquire into the intention 
of Nature we might well ask whence this triple com¬ 
plexity ? If what are called material purposes were the 
sole end of nature, a much simpler mechanism would be 
sufficient. But instead of simplicity—instead of the prin¬ 
ciple of parsimony—we have prodigality of relation and 
adaptation, and this apparently for the sole purpose of 
enabling us to see things robed in the splendours of 
colour. "Would it not seem that Nature harboured 
the intention of educating us for other enjoyments 
than those derivable from meat and drink ? At all 
events whatever Nature meant, and it would be mere 
presumption to dogmatize as to what she meant, we find 
ourselves here as the issue and upshot of her operations, 
endowed not only with capacities to enjoy the mate¬ 
rially useful, but also with others of indefinite scope 
and application, dealing alone with the beautiful and the 
true. 
PREMIUM LIST OF THE SOCIETY OF ARTS. 
The Council of the Society for the Encouragement 
of Arts, Manufactures and Commerce have just issued 
•the “ Premium List for the Sessions 1873-4-5.” In their 
address they say that they are aware that some of the 
suggestions put forth may, at first sight, appear difficult 
of realization. “ In some instances the thing sought in¬ 
volves the use of known substances in the industrial arts 
in a manner in which they are not at present employed, 
but in which there is reason to believe they are capable 
of being used with economy. In other cases the aid of 
the chemist is sought to develope such a form of action 
upon the material used as will induce the creation of new 
industries, or aid the extension of old ones by economiz¬ 
ing processes, render them less detrimental to health, or 
lessen the risk of accident to those employed. Steam 
is the motive power now generally employed, but its 
use on common roads seems at present, for various 
reasons, inadmissible. Other agents, such as mercury, 
gunpowder and petroleum have been tried, but hitherto 
without success. There are, however, many other 
materials in nature to which scientific men and others 
may well turn their attention for the development of 
power, and put them in a form which shall render them 
available to the engineer and mechanist.” 
First on the list of the subjects for which prizes are 
offered we find some relating to economy in the use of 
coals for domestic purposes. They arc— 
1. For a new and improved system of grate, suitable 
to existing chimneys as generally constructed, which 
shall, with the least amount of coal, best answer for 
warming and ventilating a room.— The Society's Gold 
Medal ancl Fifty Pounds. 
2. For a new and improved system of grate, suitable 
to existing chimneys as generally constructed, which 
shall with the least amount of coal, best answer for 
cooking food, combined with warming and ventilating 
the room.— The Society's Gold Medal and Fifty Founds. 
3. For the best new and improved system of apparatus 
which shall, by means of gas, most efficiently and 
economically warm and ventilate a room.— The Society's 
Gold Medal and Fifty Pounds. 
4. For the best new and improved system of apparatus 
which shall, by means of gas, be best adapted for cook¬ 
ing, combined with warming and ventilating the room.— 
The Society's Gold Medal and Fifty Pounds. 
5. For any new and improved system or arrangement 
not included in the foregoing, which shall efficiently and 
economically meet domestic requirements.— The Society's 
Gold Medal and Fifty Pounds. 
The Council reserve to themselves the right of with¬ 
holding all or any of the above prizes, as the judges 
appointed by them may determine. 
Preserved Fresh Meat. —The sum of £100, placed at 
the disposal of the Council by Sir W. C. Trevelyan, 
Bart., with the Society’s medal, is offered for the dis¬ 
covery of a process for preserving fresh meat in an un¬ 
cooked or raw state better than by any method hitherto 
employed, applicable to the preservation of meat in 
countries where it is now almost valueless, so as to ren¬ 
der it an article of commerce. 
Uninflammable Wood. —The Society’s Gold Medal is 
offered for the economic production of an uninflammable 
wood, so as to render buildings in which it is employed 
less destructible by fire. 
A Gold Medal is offered for the discovery or manu¬ 
facture of a means for safely and economically generat¬ 
ing power suitable for use in place of steam. It should 
be free from refuse, noxious fumes, and injurious effects 
on the metals with which it may be brought into con¬ 
tact, or on the workmen employed. 
Among the general prizes of gold and silver medals 
are— 
Coating Vessels. —For an economical method of coating 
lai’ge vessels of zinc, such as baths, so as to present a 
bright and clean surface not readily oxidizable, and as 
durable as a tinned or japanned surface. 
Vacuum. —For the introduction and use of a vacuum, 
for the drying and preservation of fruits and vegetables, 
either with or without heat of low temperature. 
Vacuum. —For any new and economic application of a 
vacuum in the preparation or finish of manufactured 
goods. 
Plastic Tubing. —For an elastic material for tubing 
suited to the conveyance of gas, and not liable to be 
affected by moisture, alterations in temperature, or to 
be acted upon by the gas itself. 
Improved Chemical Balance. —For the best chemical 
and assay balance, suitable for the use of students and 
experimentalists, which (loaded with COO grains in each 
pan) will show a difference of '005 or less. To be sold 
at a moderate price. 
