BETWEEN THE VISCOSITY OF LIQUIDS AND THEIR CHEMICAL NATURE. 101 
B. Comparison of Viscosity Magnitudes at Temperatures of Equal Slope. 
Esters. 
Viscosity-Coefficieuts. 
»/ iu dynes per sq. cm. 
X 105. 
Molecular Viscosity. 
t] in dynes per sq. cm. 
X specific mol. area, 
in sq. cm. X IU*. 
Molec. Viscosity Work, 
in dynes per sq. cm. 
X specific mol. vol., 
in cb.c. X lO'k 
Methyl. 
Ethyl. 
Propyl. 
Methyl. 
Ethyl. 
Propyl. 
Methyl. 
Ethyl. 
Propyl. 
Formate. 
345 
336 
336 
538 
635 
734 
212 
276 
344 
Acetate. 
327 
333 
613 
713 
822 
265 
333 
408 
Propionate. 
334 
336 
. . 
720 
822 
. . 
334 
407 
. . 
Butyrate. 
338 
• • 
. • 
826 
« • 
• • 
408 
. . 
. . 
Isobutyrate .... 
335 
• • 
• • 
819 
• • 
• • 
405 
• • 
• * 
Ethers, 
Viscosity-Coefficients. 
)) in dynes per sq. cm. 
X 105. 
Molecular Viscosity. 
■)) in dynes per sq. cm. 
X specific mol. area, 
in sq. cm. X 10*. 
Molec. Viscosity Work. 
t] in dynes per sq. cm. 
X specific mol. vol., 
in cb.c. X 10®. 
Methyl propyl. 
302 
648 
300 
Ethyl propyl .... 
310 
755 
373 
Dipropyl . 
318 
865 
451 
Diethyl. 
295 
635 
295 
Methyl isobutyl . 
311 
757 
374 
Ethyl isobutyl.... 
312 
849 
444 
It will be seen, in the case of both esters and ethers, that the viscosity-coefficients 
at temperatures of equal slope are fairly concordant amongst themselves, and tend, 
in the case of the ethers, to become larger with increase of molecular weight. In 
the case of the ethers—diethyl and methyl propyl—the symmetrical compound, 
under all conditions of comparison, has the smaller value; in this respect the ethers 
resemble the ketones. 
As in the case of the comparisons at the boiling-point, the formate has a larger 
molecular viscosity than any of the isomers (compare ethyl formate and methyl 
acetate ; propyl formate and ethyl acetate)—another indication of the specific influence 
exerted by the formyl group. The values of other normal esters obey the rule that 
the more nearly the number of carbon atoms in the acid radicle approximates to the 
number in the alcohol radicle the lower is. the molecular viscosity. Methyl isobutyr¬ 
ate gives a smaller value than methyl butyrate ; a similar result was found in the 
case of six comparisons in our previous paper. 
