46 
SIR J. F. W. HERSCHEL ON THE CHEMICAL ACTION OF THE 
fluence ; repetition of the sign indicating a greater intensity of the observed effect, 
whether exalting or depressing. The third column gives the characteristic ingredient 
of the chemical preparation used for rendering the paper sensitive, and the fourth 
the description of paper employed. 
No. of 
Paper. 
Character of 
Effect. 
Characteristic Ingredients of Preparation. 
Sort of Paper. 
12 
+ + + 
Simple nitrate of silver 
Thin post, of very even texture. 
694 
+ + 
Ditto 
Unsized white paper. 
570 
0 
Ditto 
Smooth demy. 
583 
+ + + 
Borax 
Smooth thick wove post. 
614 
0 
Ditto 
Smooth demy. 
593 
+ + 
Tartrate of antimony 
Thick wove post. 
59S 
+ + + 
+ 
Rochelle salt 
Smooth demy, 
Thick wove post. 
582 
Phosphate of soda 
580 
+ 
Hydrocyanic acid 
Smooth demy. 
581 
+ 
Bicarbonate of soda 
Thick wove post. 
571 
0 
Hydrobromate of potash 
Smooth demy. 
0 
Unknown, but supposed hydrobromate of potash . . 
Specimen prepared by Mr. Talbot. 
Thick wove post. 
545 
— — 
Muriate of soda 
550 
— 
Ditto 
Thin post. 
547 
0 
Ditto 
Ditto. 
556 
+ 
Ditto 
Smooth hotpressed note-paper. 
584 
— 
Ditto 
Chinese paper. 
603 
+ 
Ditto 
Thick post, a different sort from 545. 
607 
0 
Ditto 
Smooth demy. 
623 
— — — 
Ditto .... 
Blue wove post. 
579 
— 
Citrate of ammonia 
Smooth demy. 
578 
— 
Oxalate of ammonia 
Ditto. 
609 
— — — 
Muriate of soda over acetate of lead 
Ditto. 
610 
— — — 
Muriate of soda over nitrate of lead 
Ditto. 
613 
— 
f Phosphate of lime precipitated from solution of 1 
\ nitrate of urea / 
Ditto. 
Whether these facts have any connexion with the properties of colourless liquids 
discovered by M. Malaguti, I am unable to conjecture, my knowledge of his ex- 
periments being derived merely from verbal report. 
VIII. Description of an Actinograph , or self-registering Photometer for Meteorolo- 
gical purposes. 
118. As I do not mean this paper for a regular treatise, as on the contrary it pre- 
tends only to be a mere collection of insulated facts, observations, and processes, I 
maybe pardoned for inserting in this place an application which very early suggested 
itself, and which, as far as I have tried it, proved satisfactory in its working, viz. 
that of a self-registering meteorological photometer or actinograph. The objects of 
such an instrument, which cannot but be one of material importance to the meteo- 
rologist, the botanist, and the general physiologist, may be considered as two-fold, 
viz. 1st, to obtain a permanent and, at least, self-comparable register and measure of 
the momentary amount of general illumination in the visible hemisphere which con- 
stitutes daylight ; and 2ndly, to obtain a similar register of the intensity, duration, 
