Intelligence and Miscellaneous Articles. 407 



fully wiped clean with cotton, and aided, if necessary, with dilute 

 sulphuric acid ; and I pass such two plates five or six times hetween 

 a pair of smooth hardened rollers. I then anneal the plates by heat- 

 ing them to a low red heat and permit them to cool. Then I again 

 subject them to the acid process, and then I pass them, silver face to 

 face, between the rollers, the rollers being set slightly closer together 

 as the plates will have become somewhat thinner, and I repeat such 

 rolling and annealing till I find the silver surfaces are highly polished 

 and equal in appearance all over the silver surfaces. They will then 

 be ready for the next process, which consists in taking a small bunch 

 or tuft of cotton, and dipping it into dilute nitric acid, and then into tri- 

 poli, and very lightly rubbing the silver surface of a plate, then quickly 

 and carefully rubbing off the acid and tripoli with dry cotton : in these 

 rubbings a circular motion is to be observed. I then take a surface of 

 velvet, having dusted on it some impalpable powder of charcoal from 

 a muslin bag, and rub the silver surface of the plate in a direction 

 transversely of the length of plate, when the required surface will be 

 obtained, and is ready to undergo the iodine process, as is well under- 

 stood ; but I prefer that the iodine should not be used separately, 

 but that it should be combined with nitric acid and water, or with 

 bromine, or with both, or with bromic acid ; and I perform this ope- 

 ration in the following manner : I place a square glass vessel somewhat 

 larger than the plate to be operated on, in a box made of wood, 

 with a cover with an opening at each end to allow of a plate of glass 

 to slide closely across, so as to permit of as little escape of vapour as 

 possible, the plate glass slide being somewhat more than twice the 

 length of the box, and in one part thereof, towards one end, an open- 

 ing is formed through the glass large enough to receive the metal 

 plate and yet not to allow it to drop through ; by this means the slide 

 can bring the plate of metal directly over the box, in order that the 

 vapours as they arise may come in contact with the silver surface, 

 which is placed downwards, and in a few seconds it will be ready to 

 be put into the reflecting apparatus, to receive an impression, or it 

 may be put in* a suitable dark case for holding several such plates 

 ready for use. In combining iodine with nitric acid and water, I put 

 equal parts of iodine, nitric acid, and of water, and in combining 

 bromine therewith, I combine an equal part with each of the other 

 three, or I omit to use nitric acid, and use sulphuric acid and water, 

 or I omit the use of acid and simply combine iodine and bromine in 

 the box above mentioned, and the required vapours will quickly ope- 

 rate on the metal plate, the other portion of the glass slide closing 

 the box, when no plate is being operated on. And I have only 

 further to remark, that when the impression has been obtained, the 

 plate is to be operated on by the mercury, and the fixing and wash- 

 ing processes, in like manner to the treatment well understood when 

 treating plates which have, according to the process of Daguerreo- 

 type, received an impression or image by the aid of a camera, all 

 which is well known, and in use, and forms no part of the invention. 

 In taking impressions or obtaining images by the aid of the apparatus 

 above described, it is desirable to use a screen behind the person 

 sitting to have a likeness taken, and for this purpose a plate of ground 



