492 



NOTES AND QUEEIES. 



[No. 295. 



leaves, and lay them out to dry spontaneously; This 

 paper maj- be' kept for any length of time if it be well 

 washed ; but if any acid be left in it, it causes a change, 

 and I have even known samples which have undergone a 

 sort of slow combustion months after being made, I sup- 

 pose from this cause. 



Of this paper, when well dried (which must not be 

 done near the fire, on account of the inflammability of 

 the material), take 250 grains, and having placed it in a 

 bottle containing a quart imperial of the best washed 

 ether, add three ounces of alchohol at 96 to 98 p. c, and 

 shake the bottle constantly till the paper is completely 

 dissolved. Should the preparation of the paper not have 

 been quite correctly done, or should an inferior quality of 

 paper have been employed in the first instance, the solu- 

 tion may ba perhaps only partial in such a case. Having 

 let the liquid stand for two or three days, pour off the 

 clear liquid from the sediment, and then by adding to it 

 more of the paper we may hope to produce a collodion of 

 the requisite thickness ; but 1 can' of course give no exact 

 rule, as the quantity added will of course be proportionate 

 to the quantity first taken up by the ether. The best 

 plan is to prepare a fresh lot of paper, and if sufficiently 

 careful abo\it the strength of the acids, the temperature of 

 the liquid, and the quality of the paper, you may depend 

 on succeeding. 



The collodion thus prepared must be allowed to stand, 

 in order to let any little hairs or other substances settle 

 to the bottom of the bottle; it is then to be poured off 

 into another bottle, in which has been placed lialf an 

 ounce of carbonate of potash, pure and dry and in powder. 

 This being shaken up in the collodion, is to be allowed to 

 settle again, and in a day or so the collodion should be 

 poured otf into the stock bottle. Of course, in giving 

 these proportions, 1 do not say it is absolutely necessary 

 to employ a collodion of this thickness, but only that this 

 is the proportion of paper to ether which I employ ; others 

 may prefer it thinner, and perhaps for positives on glass 

 it may be even belter. Therefore, within certain limits, 

 the operator may be guided by his own judgment as to 

 the proportion of paper he adds to the ether. The collo- 

 dion so prepared may be kept an unlimited time, pro- 

 viding it be placed in a stoppered bottle; and indeed it 

 rather improves, and becomes clearer by keeping. The 

 next preparation to be made is the iodizer, as it is some- 

 times called, which is a solution of iodide and bromide of 

 ammonium in alcohol. IMix bromide and iodide of am- 

 monium in the proportion of one part of the former to 

 four parts of the latter; and of this compound dissolve 

 250 grains in one pint of alcohol of 95 p. c. This mix- 

 ture will keep well separately, but should not be added to 

 the collodion except when the latter is about to be used : 

 when added, take one part of the mixture to three of col- 

 lodion. The collodion thus iodized will keep for a month, 

 but after that time begins to deteriorate; indeed it should 

 be employed soon after being made. A curious fact, and 

 one for which I can hardl_v account, is, that this col- 

 lodion when iodized becomes red at first ; but after stand- 

 ing some time, spontaneously gets nearly white. The 

 next thing to be prepared is the nitrate bath; which is 

 made bj' dissolving seven parts of nitrate of silver in 

 fifty parts of distilled water, adding a little of the iodizer 

 above mentioned, say half an ounce for half a pint of the 

 liquid; well shaking the bottle, and then adding fifty 

 parts more of water, and filtering. A mixture of Tripoli 

 powder is also to be made in a wide-mouthed stoppered 

 bottle, with some alcohol : and now all the chemicals are 

 prepared for the first part of the process. The bath I use 

 is a horizontal one, which I prefer to the vertical, and is 

 very simple to make and to use. It is an ordinary gutta 

 percha tray, the sanie width as my plate, and a little 



longer than the plate ; one end is covered in, so that when 

 the bath is placed vertically, this end forms a kind of 

 trough, holding just enough liquid to cover the plate 

 when it lies flat in the bottom of the bath. The plates 

 should be made of thin plate glass, and the edges ground 

 all round, and the corners in the least degree rounded; 

 and they should be well cleaned, first with pure water, 

 and next with a bit of cotton-wool and the Tripoli and 

 alcohol above mentioned. When I wish to sensitise a 

 plate, I wipe it with a clean linen cloth ; and lastly, brush 

 it with a small flat brush, which should be kept for the 

 purpose, and free from dust, as I find it serves best ta 

 remove any hairs which may adhere to the plate from the 

 cloth with which it is wiped Then hold it in the left hand 

 by one corner, or, better still, fix it on one of the pneu- 

 matic plate-holders ; and keeping it in a horizontal posi- 

 tion, pour on its face some of the iodized collodion, make 

 it flow to all the sides of the plate by inclining the latter 

 in various directions; and lastly, pour it off by one corner 

 into the bottle, and be very careful to keep the plate con- 

 tinually oscillating from side to side in the neck of the 

 bottle, so that the streaks of collodion, which forms as it 

 runs off^, may run one into the other. If this be well done, 

 the surface will look so fine, as to make it difficult to say 

 which is the collodion side. As soon as the collodion 

 begins to get firm by the evaporation of the ether, the 

 bath is to be lifted up' by the end which is not covered in, 

 so as to cause the nitrate solution to flow into the well at the 

 end; and the plate is to be placed flat against the bottom 

 of the bath (there should be two little bits fixed in the 

 bottom of the bath, so that when the plate is placed in it, 

 and while the bath is still in a vertical position, the plate 

 maj' be kept up towards the end by which the bath is 

 held, and away from the well). The bath is then let 

 down into its horizontal position, and the liquid flows 

 instantly and evenly out of the well over the surface of 

 the plate. 



This operation of sensitising the plate must be con- 

 ducted in a room lighted only W a yellow light ; and for 

 this purpose nothing more is wanted than to nail a piece 

 of yellow calico, double folded, against the window. 

 Having then thus immersed the plate, I now move the 

 bath up and down, in order to wash the surface well with 

 the liquid ; and after a few minutes of such treatment, it 

 will be found that the plate, which at first seemed to repel 

 the liquid as if greasy, becomes wetted evenly all over; 

 when this occurs, the "plate is to be raised from the bath, 

 which mav be done by placing the latter upright, so that 

 the liquid'flows back" into the well, and then lifting the 

 plate out. 



The plate is now ready for the dark slide, in which it 

 may be placed for exposure ; or, as I am about to describe 

 it, may be rendered more sensitive by pouring oyer it a 

 prepared syrup ; or it may be preserved for a considerable 

 period by a process which I will also give. 



F. Maxwell. Lyte. 



Bagn^res de Bigorre, Basses-Pyreneesi. 



(To be continued.) 



3SitpUti ta Minav ^utxiti. 



Naturalisation Laws (Vol. xi., p. 445.). — By 

 statute 7 & 8 Vict. c. 66., entitled " An act to 

 amend the laws relating to aliens," the home se- 

 cretary is empowered to grant a certificate of 

 naturalioation to any foreigner, which entitles him 

 to vote, hold freehold property, and all the rights 



