Oct. 23. 1852.] 



NOTES AND QUEEIES. 



397 



monio-nitrate of silver process, not by mere salting, as 

 described at p. 372., but by immersing it in the follow- 

 ing solution of sugar of milk or mannite : 



Common salt - - - 10 grains. 



Muriate of baryta - - 10 grains. 



Sugar of milk - - - 2 drachms. 



to be dissolved in one pint of boiling rain or distilled 

 water, and used when cold. This paper being ex- 

 cited by the ammonio-nitrate of silver, as already de- 

 scribed, the picture is to be printed rather strongly, 

 and then washed in old hyposulphite of soda solution, 

 m which sel d'or is dissolved in the proportion of one 

 grain to every eight ounces of the solution. 



The ignition alluded to by our correspondent is of 

 course only suclj as would take place by bringing a 

 lighted candle near turpentine, spirits of wine, brandy, 

 or any similar body.] 



Manufacture of Lenses. — To form single achro- 

 matic lens of concave flint glass, corrected by 

 convex of crown glass, four inches aperture for 

 the paper processes. 



What are the proper curvatures, indices of re- 

 fraction, and dispersive powers ? A Subscriber. 



Having a great desire to make collodion for my 

 own use (having been informed by a first-rate 

 photographer that only under such circumstances 

 can success be calculated on), I was rejoiced to 

 find in your paper that Dr. Diamond had pre- 

 sented to its readers instructions for the making of 

 collodion. But in two places he has omitted to 

 state the proper quantities of ingredients, on the 

 proper adjustment of which, it seems to me, the 

 success of the experiment very much depends. I 

 mean, first, as to the quantity of iodide of potas- 

 sium to be dropped into the iodide of silver, in 

 order to re-dissolve it. Secondly, what quantity 

 of the protonitrate of iron is to be added to the 

 pyrogallio mixture ? If it were compatible with 

 Dr. Diamond's plan, and not too great trouble, 

 the information would, I have little doubt, be 

 acceptable to hundreds of other tyros in photo- 

 graphy as well as to myself 



Having found the staining of the fingers a great 

 annoyance, I devised a tray for holding the glass 

 when developing. It is made of gutta percha, one 

 inch deep at the sides, and the ends cut to a curve 

 a little below the triangular brackets, in order that 

 the placing of the glass may be done with facility, 

 and that the acid may not lodge, which might dis- 

 turb the adhesion of the film. There is a handle at 

 the left side for the finger and thumb of the left 

 hand of the operator. T. L. Mjerritt. 



Maidstone. 



[Mr. Merritt's arrangement is a very ingenious one, 

 but is scarcely needed if the operator uses the glass a 

 little longer than is absolutely required, as recom- 

 mended in Dr. Diamond's former article, p. 295. He 

 is informed that it is impossible to determine the exact 

 quantity of iodide of potassium which will be required 



to dissolve the iodide of silver. It should be added 

 cautiously, and being very soluble, when sufficient has 

 been added the solution becomes perfectly clear, in con- 

 sequence of the solution of the opaque iodide of silver. 

 In reply to his second Query, he is informed that 

 equal portions of the protosulphate of iron and pyro- 

 gallic acid solution may be added together for the 

 purpose of development, but not more than is abso- 

 lutely requisite to flow freely over the plate should be 

 used, because the small portion of solution of nitrate 

 of silver then adhering to the collodion film appears to 

 be much weakened, and the picture does not develope 

 so effectually. By many operators it has been recora- 

 mended to drop a few drops of the nitrate of silver 

 solution into the pyrogallic acid; but it is apt to stain, 

 and often produces an unpleasant precipitate over the 

 whole surface of the plate.] 



GUANO AND THE LOBOS ISLANDS. 



(Vol. vi., p. 336.) 



I beg permission to introduce to P. C. S. S., and 

 to your other readers, a passage which appeared 

 in print sixty-six years earlier than that which 

 your correspondent has brought forward, and be- 

 lieves to contain the earliest English mention of 

 guano. It occurs in the translation of the Spanish 

 Jesuit, Joseph de Acosta's Historia natural y 

 moral de las Indias, published in the year 1604, by 

 E. G., the initials, it is supposed, of Edward 

 Grimestone, under the title of the Naturall and 

 Murall Historie of the East and West Indies. 



Acosta had resided seventeen years in Peru, and 

 his work was first printed at Seville in 1590. The 

 extract (at p. 311.) is as follows : 



" There are other birdes at the Indies, contrarie to 

 these, of so rich feathers, the which (besides that they 

 are ill favoured) serve to no other use but for dung ; 

 and yet perchance they are of no lesse profite. I have 

 considered this, wondering at the providence of the 

 Creator, who hath so appointed that all creatures 

 should serve man. In some islands or phares, which 

 are joyning to the coast of Peru, wee see the toppes of 

 the mountaines all white, and to sight you would take 

 it for snow, or for some white land ; but they are 

 heapes of dung of sea fowle, which go continually 

 thither ; and there is so great abundance as it riseth 

 many elles, yea, many launces in height, which seemes 

 but a fable. They go with boates to these Hands, onely 

 for the dung, for there is no other profit in them. And 

 this dung is so commodious and profitable, as it makes 

 the earth yeelde great aboundance of fruite. They cal 

 this dung guano, whereof the valley hath taken the 

 name, which they call Limaguana*, in the valleys of 

 Peru, where they use this dung, and it is the most 

 fertile of all that countrie. The quinces, poungraiiets, 

 and other fruites there, exceede all other in bountie 

 and greatnes : and they say the reason is, for that the 

 water wherewith they water it passeth by a land com- 

 passed with this dung, which causeth thebeautie of this 



* Lunaguana in the originaL 



