Geology. 135 



the plate from the dipper, as recommended by my friend F. F. Thompson, 

 Esqr. (see Seely's Journal for May, 1862). After being thus washed 

 with water it is flowed with or dipped into a bath composed of fifteen 

 grains of Tannin dissolved in each ounce of pure water, the solution being 

 carefully filtered. The plate should remain in this bath four or five miu- 

 utes. It is then drained, and set up on one corner, on .bibulous paper, to 

 dry in a dark room or box. The ordinary exposure necessary is about 



alcohol. No. 2. Nitrate of silver 20"grains, citric acid 40 grains, pure 

 water one ounce. To develop— wet the plate rapidly with pure water, 

 when the film is thoroughly moistened, flow the plate with water, to 

 each drachm of which has been added two drops of No. 1, and one drop 

 of ^0. 2 ; keep this developer in motion over the plate until the details 

 are well out, then add to it drop by drop of No. 2, until the required 

 intensity is obtained. Fix in hyposulphite of soda as usual. 



Experience in the use of this process teaches— 1. That drying by arti- 

 ficial heat is not necessary. 2. That the amount of acid in No. 2 may be 

 judiciously varied with the length of exposure. It is better to have an 

 excess of acid than too little. 3. Warming the plate in a bath of water 

 aeated 90° F., but using the developing solutions at the ii 

 as/ecomraended by Dr. Draper, of Ne' " ' 



ot exposure necessary, so that this process may be worked almost as 

 ifpidly as the wet. 4. By the use of honey in combination with the 

 |anuin, fifteen grains of each to the ounce of water as recommended by 

 y- England, of London, great rapidity is gained. 5. A brorao-iodized 

 joiiodion is to be preferred, and an old collodion works better in my 

 J^aDjIs than a new .sample. 6. The silver bath should not be neutral, but 

 ought to be decidedly acid ; this may be done by adding one drop of nitric 

 a«id for every twelve ounces of bath. 7. This process is peculiarly 

 »J?Pted to the production of glass transparencies for the Stereoscope, 

 anording great beauty and richness of tone. 



II, GEOLOGY. 



Jk^^'^^^^y 0/ Vermont.~^Q would call attention again to the Report 



r^ the Geology of Vermont, noticed in our last volume. The work is in 



1 .V"^ ^™^^ quarto, in all 990 pages, with numerous illustrations, besides 



" '"' '"^^ geological map of the State, and is offered for the moderate sum 



lollars. The geology of Vermont has a special interest on account 



ntimate connection within the borders of the State, of raetamor- 



- ' fossiliferous rocks, and in some cases the occurrence of the latter 



•"^ath the former, or the one passing into the other. Ihe volumes 



:r ^""^at very fuHj of the phenomena of the drift, of the river and lake 



^ 'races elevated sea-beaches, and the fossils of the post-tertiary; also 



;; J"gth of the economical products of the state. With regard to copies 



V ^^ ^ofk, letters should be addressed to Albert D. Eager, Proctorsville, 



^«j|mont. 



- '^istodon tooth in Amador Co., Ca^t/omw.— Remains of the raasto- 



'; been very rarely found in California. Dr. Logan 



-' us two photographic views of what appears to b€ 



