5. The developing agent with the pyrogallic and formic acids will keep good a very long time, longer, I think, than that in which acetic acid is used, but cannot be used as a dipping bath. 6. I find the formic acid which I obtain from different chemists rather variable in its strength. What I use is rather below the average strength, so that in general about six drachms of the commercial acid will suffice where I use one ounce; but the excess seems to produce no bad result. 7. A great advantage of the pyrogallic developer which I recommend, is that of its being able to be diluted to almost any extent, with no other result than simply making the development slower. Another point is also worthy of notice, viz. a method by which even a very weak positive on glass may be converted into a very strong negative. I take a saturated solution of bichloride of mercury in hydrochloric acid, and add of this one to six parts of water. This I pour over the collodion plate, and watch it till the whitening process is quite complete. Having well washed the surface with water, I pour over it a solution of iodide of potassium, very weak, not more than two or three grains to the ounce of water. The effect of this is to turn the white parts to a brilliant yellow, quite impervious to actinic rays. This process is only applicable to weak negative or instantaneous pictures, as, if used on a picture of much intensity, the opacity produced is too great. By using, however, instead of the iodide of potassium, a weak solution of ammonia, as recommended by Mr. Hunt, a less degree of intensity may be produced again a less intensity by hyposulphate of soda and a less degree again, but still a slight darkening, by pouring on the bichloride and pouring it off at once before the whitening commences. I thus can tell the exact degree of negative effect in any picture of whatever intensity. The terchloride of gold is most uncertain in its results, at any rate I find it so. I must again beg you to excuse the great length of my communication, and hope it will be of service to my fellow photographers. F. MAXWELL LYTE. Florian, Torquay. * * * * * Replies to Minor Queries. _Derivation of the Word "Island_" (Vol. viii., p. 49.).--I have received through the kindness of Hensleigh Wedgwood, Esq., a copy of the _Philological Journal_ for Feb. 21, 1851, in which my late observations on the etymology of the word _island_ are shown to be almost identical with his own, published more than two years ago, even the minutest particulars. His own surprise on seeing my remarks must have been at least as great as my own, on learning how singularly I had been anticipated; and those of your readers who will refer to the number of the journal in question, will be doubtless as much surprised as either of us.