It is about four-feet six-inches high, and carries a small table on 

 which the camera is placed. There are several varieties, differing 

 in their construction and price. 



CHEMICALS. 



These should be all of the best quality, and should only be 

 purchased of respectable parties who will guarantee their purity. 

 Cheap chemicals are seldom economical, as the adulteration of any 

 of them will interfere most annoyingly with the successful prose- 

 cution of the experiment. The following list comprises almost 

 every article required in the processes hereafter described. 



* Nitrate Silver in chrystals 

 Iodide Potassium 

 Bromide Potassium 

 Hyposulphite Soda 

 Pure Gallic Acid 



Succinic Acid 

 Proto-sulphate Iron 

 Ammonia-citrate Iron 

 Ferro-sesquicyanuret Potassium 

 Yellow Ferro-cyanate of Potash 

 By-chromate Potash 

 Sulphate Copper 

 Nitric Acid 

 Strong Ammonia 



THE CALOTYPE. 



The Calotype, or Talbotype is, as we have already mentioned, the 

 invention of Mr. Fox Talbot. It has been much improved since 

 its first introduction ; and to Mr. Cundell in particular we are 

 indebted for many practical suggestions, which he first communi- 

 cated to the world in the Philosophical Magazine.t In describing 

 this process, we shall, without referring to authorities, give such 

 simple directions for conducting it, as we have found from expe- 

 rience the most likely to produce satisfactory results. 



The Nitrate of Silver in solution is very easily affected by light, and should 

 be kept in a dark place, 

 t No. 160, May 1844. 



