SOLAR LIGHT AND ITS AGENCY. 
5!) 
slightest excess, had the curious property, when under the influence of light, of 
imparting a pink tinge, and the slightest approach to redness would allow the free 
passage of those rays it was so important to obstruct. 
Mr. Hunt is the author of those scientific papers on " The Physical Powers of 
the Universe," which have, during a considerable period, been published in the 
" Pharmaceutical Times." His writings are doing Science good service ; and now, 
this paper upon the " Effects of Light in Plant-houses," widely disseminated as it will 
be in the columns of the " Gardeners' Chronicle," will tend to improve the practice of 
plant-culture. Reference may also at any time be made to the great example thus 
furnished at Kew. 
The theory thus advocated, leads to one remark upon the effects of coloured glass. 
If the blue ray be the agent of magnetism, and the red ray be the medium of 
electricity, while rays invisible, but still adjoining those red rays, possess a yet 
greater heating power, may we not presume that the two produce those chemical 
effects which correspond with electric polarity? The subject claims the utmost 
attention. To conclude our extracts, the following is given verbatim : — 
" From the facility with which we were enabled to regulate the use of coloured 
media, the quantity of either light, heat, or actinism, which may be admitted to 
growing plants, we had the command of means of supplying the increased action of 
any of these forces. Germination might be quickened by the action of the actinic 
power, independently of light, and the full action of chemical rays was secured by 
the use of glasses stained blue by cobalt. In all cases the germination of seeds 
may be quickened by covering them with such blue glass as was used in making 
many finger-glasses ; and since the striking of cuttings was dependent upon the 
exercising of an analogous force to that which quickened germination, similar glass 
shades would be found to effect this object. It must, however, be remembered that 
the excitement of that chemical agent must be withdrawn after germination has been 
effected, the roots formed, and an independent existence given to the plant." 
It is to be regretted that the agent of actinic force is not more clearly defined : 
judging, however, from the closing hypothetical paragraphs, the curious reader may 
be enabled to infer that the actinic rays are not luminous ; for we read, that " the 
absence of luminous rays in considerable quantity, and a diminished quantity of the 
chemical or actinic radiation might be secured at will without interfering with the 
heat-giving principle, by the use of glasses coloured red by the oxide of gold." But 
this red tint, even the pink hue from manganese referred to above, would seem to 
compromise the principle advocated throughout, namely that of excluding the 
scorching agency, Great difficulty is involved every way ! Again it is stated that 
the yellow glasses obstructed the chemical rays, but would intercept very little light : 
therefore, " when there was any tendency to form too much stalk or leaves, and it 
was desired to produce more wood, it was done by admitting as much light as 
possible, with the smallest possible quantity of actinic power, and that might be 
effected by interposing glasses of a yellow tint." 
