82 The American Naturalist. [January, 
MICROSCOPY." 
Formol as a Preserving Fluid.’—If the four atoms of hydro- 
gen in the simple organic combination, swamp gas or methan, be 
replaced by a hydroxyl group there may be formed, one after the 
other, partly by the separation of water, (1) methylalcohol, (2) 
methylenglycol, (3) formic acid, and (4) carbon dioxide. The process 
may be illustrated in the following manner : 
H 
| 
H—C—H = CH, = methan. 
OH 
| 
H—C—H = CH,O = methylalcohol. 
| 
H 
OH 
| 
H—C—OH = CH,O, = methylenglycol ; and CH,O,—H,0 = 
| 
H 
CH,O = formaldehyde. 
OH 
| 
H—C—OH = CH,0, ; and CH,O,—H,0 = CH,0, —formie acid. 
| 
OH 
OH 
| 
OH—C—H = CH,0,; and CH,O,—2H,0 = CO, =carbon dioxide. 
| 
OH 
Of these five combinations it is formaldehyde that concerns us. It 
was discovered in 1863 by A. W. Hoffmann while passing wood spirit 
(methylaleohol) and air over a red hot platinum spiral. If the vapor 
1Edited by C. O. Whitman, University of Chicago. 
2? The first half of this paper is a free translation of a paper by Prof. T. Blum in 
the Bericht. über d. senckenbergische naturf. Gesell. in Frankf. a. M., 1894, p- 
195.—F. C. K. 
