6 THE MICROSCOPE. [January, 



solution ; one sheet of ferrotype plate ; squegees ; broad camel's- 

 hair brush; plates; plate-holder; focusing glass; camera; a 

 pair of scales suitable for weighing grains ; card mounts ; parlor 

 paste ; and negative varnish. 



The following chemicals are needed : i lb. each of sulphite of 

 sodium, carbonate of potassium, chrome alum, hyposulphite 

 of sodium, and carbonate of sodium ; one ounce each of sul- 

 phuric acid, bromide of potassium, caustic soda, pyrogallic acid, 

 and hydrochinon. 



Several other things, such as a drying rack, intensifier, etc., 

 could be added with advantage. To those who are financially- 

 able I would say select a good serviceable camera with several 

 kits and one arranged for manipulating the micrometer screw at the 

 end. With this instrument different sized plates may be used, 

 and there is a certain satisfaction in using an instrument with all 

 the modern improvements, but equally good results may be 

 obtained with far less expensive apparatus ; in fact, good work 

 may be done by any one with a little ingenuity, by constructing a 

 camera to fit the plate-holder. The most convenient size is the 

 4x4 or 4x5 plate. Select a good plate-holder for the above 

 sized plate and fit it light-tight by means of a narrow ledge to a 

 board 5x6 inches, which has a circular hole three and one-half 

 inches in diameter in the centre. 



Make a paper cone of black sheathing paper, 18 inches long, 

 three and one-half inches in diameter at one end and large enough 

 at the other to admit the draw-tube of the stand or ocular. Tack 

 it to the inside of the hole in the board and at a right angle to it. 

 Fill up all the chinks with sealing-wax and paint the parts that 

 might reflect light upon the plate a dull black and we have a 

 serviceable camera at no expense except the time of making. 



Make a small frame that shall fit the board in the place of the 

 plate-holder, and which contains a piece of ground glass for 

 focusing upon, and support the whole thing firmly and perma- 

 nently upon one end of a base-board, about one foot wide and 

 four feet long, at such a height that when the microscope is 

 turned back at a right angle the upper end of the draw-tube may 

 enter therein. 



As will be inferred from the above, the proper position for the 

 microscope is to incline the body at a right angle with the base, 

 but this is rendered necessary only from the position of our 

 improvised camera and for convenience in manipulating. 



I have found Carbutt's special, quick as lightning, blue label, 

 plates to be very well adapted to the needs of this work. 

 I should recommend that one select a good plate, and not change 

 unless for some good reason, as we soon learn the peculiarities 

 of each kind, and thus are better fitted to meet with emergencies 

 and conditions which another plate might not possess. And, 



