320 HOW TO SEE WITH THE MICROSCOPE. 



APPARATUS. 



Six test tubes ; let four of these be large size. Spirit 

 lamp. Four or five two-ounce beakers. Bink's 250 

 grains burette. Two or three small glass funnels, say 

 ot two-ounce capacity. Filters to match the above. 

 Two or three glass rods. Two or 'three brushes for 

 cleaning test tubes ; ditto, for burette. Litmus paper, 

 blue and red. Two measuring pipettes, one-half, one 

 and two fluid ounces. Urinometers. 



All of the above can be obtained of Messrs. Gr. Tie- 

 man & Co., 67 Chatham street, New York, and will 

 cost less than $7.00 



Additional to this list we recommend the purchase of 

 three or four " Marais " graduated tubes for approxi- 

 mative analysis. These cost $1.50 each. At least one- 

 of these should be provided. 



A delicate balance, one turning with one-fourth grain 

 when loaded with an ounce in each pan, will be required. 

 Most of the books treating on volumetric analysis de- 

 mand that the balance should be quite an expensive one. 

 Nevertheless, the simple little models which can be pro- 

 cured almost anywhere, and costing less than $3.00, can 

 be made to answer tolerably well. Those to whom the 

 expense is not objectionable will find a really fine bal- 

 ance enclosed in a glass case a luxury. Ours, made by 

 Troemner, of Philadelphia, turning with, say one-fiftieth 

 of a grain, costing $40.00, has given excellent satisfac- 

 tion. Reliable instruments, by Becker, can be obtained 

 in the cities, at prices from $10.00 upwards. Those who 



