Section 21.118 - Methyl n-butyl ketone(a)Acidity (as acetic acid). 0.02 percent by weight, maximum.(c)Odor. Characteristic odor.(d)Refractive index at 20 °C. 1.396 to 1.404.(e)Specific gravity at 20 °/20 °C. 0.800 to 0.835.(f)Distillation range. No distillate should come over below 123 °C. and none above 129 °C.T.D. ATF-133, 48 FR 24673, 6/2/1983. Redesignated by T.D. ATF-442, 66 FR 12854, 3/1/2001