Sept. 18. 1852.] 



NOTES AND QUERIES. 



277 



commendations of this latter process, that as the 

 picture is developed on the spot, the result is 

 known at once ; whereas, in the other cases, it is 

 not until the subsequent development of the pic- 

 ture at home that the manipulator ascertains 

 whether he has succeeded or failed : so that while 

 a liailui'e in the Collodion process may be imme- 

 diately remedied by a fresh attempt, in the case of 

 the other processes such a proceeding is often im- 

 practicable. It is another greater feature in the 

 Photographic practice which I am advocating, that 

 the picture obtained is a positive — or if exposure 

 of the prepared glass plate in the camera should 

 have exceeded the period necessary to produce a 

 positive, the result will probably be a negative, 

 from which excellent positives may be produced 

 by printing. 



Postponing, therefore, for the present all consi- 

 deration of the Daguerreotype and Talbotype, I 

 will now proceed to give A. H. K. such informa- 

 tion as will, I trust, enable him, and other gentle- 

 men " desirous of taking accurate views of anti- 

 quarian remains," to accomplish so desirable an 

 object ; and this without the necessity of " carry- 

 ing their tent " with them. 



First, it will be necessary for him to provide 

 himself with a camera having loose sleeves made 

 of black jean attached to the sides, through which 

 he can introduce his hands Into the body of it (as 

 originally designed by Mr. William JBrown, of 

 Ewell), and furnished at the back with a similar 

 contrivance for the head ; so that the operator, 

 when In the open air, has in his camera all the 

 advantages of a darkened chamber ; yellow light, 

 which may be graduated according to circum- 

 stances, being admitted through a small piece of 

 yellow glass (with a sliding cover), which must be 

 inserted In the top of the camera for that purpose. 

 The camera must also be provided with a bath 

 either of glass or gutta percha, to contain the 

 solution of nitrate of silver — thirty grains to the 

 ounce of distilled water — which bath, during the 

 time of operating. Is allowed to drop Into a mov- 

 able chamber, made for that purpose at the bottom 

 of the camera, so as not to be In the way of the 

 operator. I am now constructing a camera com- 

 bining some improvements, expressly for out-door 

 operations, which when completed I shall be happy 

 to describe for the Information of your readers. 



It is so obvious that the beauty and accuracy of 

 the pictures must depend In the first instance on 

 the goodness of the image thrown on the prepared 

 glass plate, which can only be obtained by a 

 perfect lens, that great discretion should be shown 

 in the choice of one ; nor should the Intending 

 photographist be afraid of paying a liberal price 

 for that which, if impei-fect, would render all his 

 subsequent pains, trouble, and expense entirely 

 useless. 



Presuming, therefore, your Querist to have pro- 



vided himself with these essentials, a camera such 

 as I have described, and fitted with a good lens, I 

 will now proceed to tell him, first, how to prepare 

 his chemicals, and, secondly, how to make use of 

 them. 



Having tried Innumerable suggestions as to the 

 making of collodion, and having purchased it 

 wherever it could be procured, during the many 

 experiments I have performed, with the view of 

 ascertaining the collodion from which the most 

 agreeable results could be produced, I have no 

 hesitation in pronouncing collodion prepared In 

 the following way to be that best adapted for 

 general use. 



To prepare the Gun Cotton. — Place one hun- 

 dred grains of clean jeweller's cotton in a large 

 basin, and pour upon It an ounce and a half of 

 nitric acid, previously mixed with one ounce of 

 strong sulphuric acid. Frequently knead it with 

 glass rods during five minutes, at the end of which 

 time the cotton is to be Immediately plunged Into 

 cold water, and washed as long as any trace of 

 acid remains, which can be more readily detected 

 by the taste than by any other means. When 

 dried it is fit for use. The most convenient mode 

 of drying It is by first wringing it in the folds of a 

 towel, and then pinning it up in small portions to 

 allow the air to have free access to It. 



To prepare the Collodion. — About fifty grains 

 of this cotton put Into a pound of ether will dis- 

 solve and form collodion of the required consis- 

 tency. The ether used should be the common, 

 rectified ether, not washed; and should the ope- 

 rator find he has obtained an ether which will not 

 dissolve the cotton, a portion of spirits of wine may 

 be added in a proportion not exceeding one-tenth 

 of the ether. This may be either allowed to sub- 

 side, or be strained off immediately through an old 

 silk handkerchief, and is then in a fit state to 

 iodize. 



To iodize the Collodion. — Form an iodide of 

 silver by separately dissolving thirty grains of 

 nitrate of silver and thirty grains of iodide of po- 

 tassium, each in four ounces of distilled water. 

 Professor Hunt has clearly shown that a more 

 sensitive iodide is produced by a free dilution of 

 these salts. When mixed, the iodide of silver is 

 precipitated of a pale brimstone colour, which pre- 

 cipitate should be frequently washed with distilled 

 water, and when almost dry placed In a bottle 

 containing one ounce and a half of alcohol. Iodide 

 of potassium being then dropped into this mixture, 

 the iodide of silver is re-dissolved, and when per- 

 fectly so it is fit for use. It is difficult to deter- 

 mine the exact quantity of this solution which 

 will be required to properly Iodize the collodion, 

 probably about ten or twelve drops to every 

 ounce. But It should be added until the collodion, 

 when poured on a piece of glass and Immersed in 

 the bath of nitrate of silver, assumes a semi-opaque 



