The Microscope. 179 



sam added and the cover applied. " In this way ten or twelve 

 sections can be prepare4 in a day." 



Emerson as a Microscopist. Dr. Oliver Wendell Holmes 

 mentions in his biography of Emerson, just published, that 

 in 1833 Emerson visited Europe for the first time, and 

 while there called upon Prof. Amici, who showed him his 

 microscope, magnifying (it was said) two thousand diameters. 

 Dr. Holmes says : " Emerson hardly knew his privilege ; he may 

 have been the ihrst American to look through an immersion lens 

 with the famous Modena philosopher."" 



Long Tubes. W. J. Lancaster says we are to have a length- 

 ening tube by all means. He has used tubes two feet in 

 length with most excellent results, although all objectives will 

 not stand it. One diaphragm should be used for about every 

 nine inches of tube, otherwise internal reflections will spoil the 

 definition. 



Siliceous Cement, for protecting corks from the fumes of 

 acid, etc. Mix together equal parts of colloid silica and thick 

 gum- water, with sufficient gilder's whiting to make it of the con- 

 sistency of treacle. 



For Labelling Slides. — A good plan is to punch some 

 squares or circles out of very thin talc; cover the end of the 

 glass slip with a thin layer of gilder's whiting and gum-water ; 

 when dry, write on this with common ink, let it dry, put a very 

 small drop of Canada balsam upon it ; cover with a circle of thin 

 talc, and allow all to dry ; then clean the edges with benzole 

 and water mixed. It will not peel off or get dirty like printed 

 labels, 



Carbolic Acid Preservative, for animal and vegetable tis- 

 sues. Carbolic acid, 1 drachm; alcohol, 2 drachms ; distilled 

 water, 12 ounces ; dissolve the carbolic acid with the alcohol, 

 then add it to the water and boil it for ten minutes, and bottle 

 for use. 



Acetate of Aluminum.— To 1 part of acetate of aluminum, 

 add 4 parts of distilled water. This is very good for preserving 

 vegetable colors, as in the case of desmids and other algae. 



Glycerine and Acetic Acid is useful for mounting many 

 minute insects and other objects ; it is composed of glycerine, 1 

 ounce ; acetic acid, \ ounce. 



