Lx eVinme cae a m { : ; to tee 
, ity Wen - Trae 3 ee Rint ee . ie 
; as BE hice. valeric acids). 
3 an Ww. Desen, H: M. Plum and J. E. Schott!) have tested the constants worked out 
eS arrived at by his aatied Whenever two acids are present in the se rabiege’ 
results oo are rather unreliable, and if one of the acids is present in the 
Fon ine other hand, A. R. Lamb?) has found Duclaux’ method to give satis-— 
tory results in case the working conditions are strictly adhered to, the heating is 
e . by electricity and in- case not more than two or three acids are tried to be 
fe nined in one fraction. ‘In determining the constants. of the acids, careful ‘puri- 
ication of the latter is essential. 
4 According to H. Droop Richmond’), Duclaux’ method is useful for determining 
ytic acid in acetic anhydride, and by combining Duclaux’ process with the usual 
4 imetric methods a sample of acetic anhydride may be eotay eu as to its content 
of anhydride, acetic and butyric acids. 
_ - Furthermore, it might here be mentioned that J. K. Phelps and H. E. Palmer“) have 
designed a method for separating and estimating butyric acid. From a mixture with 
for ic and acetic acids the former may be separated by means of its quinine salt, 
‘solt ble in carbon tetrachloride, the quinine salts of formic and acetic acids being 
insoluble in that solvent. By weighing the quinine butyrate (m. p. 77.59), the amount 
butyric acid may be calculated. The quinine salt of propionic acid shows Menus 
Same solubility in carbon tetrachloride as the butyrate. : 
_ Nothing is stated in the abstract available whether it is a matter of normal or of 
Beeatyric acid. 
% Another method for identifying and estimating butyric acid has been described 
'G. Denigés*). It is based on the formation of acetoacetic acid by treatment of 
but ic acid with hydrogen peroxide in presence of ferrous salts acting as catalysts, 
S stated by Dakin, and on the identification of the acetoacetic acid by means of 
sodium nitroprussiate. The mixture containing butyric acid is heated for 5 minutes 
to 70° with a certain amount of hydrogen peroxide and a solution of ferrous ammonium 
ulphate acidulated with sulphuric acid; then a few drops of caustic soda lye are added, 
€ Solution cooled down and filtered and a certain proportion of the filtrate is mixed 
wi a some drops of caustic soda solution, a few drops of a 5 per cent. sodium nitro- 
prussiate solution and a. slight excess of acetic acid. There results a red coloration, 
intensity of which is in proportion to the butyric acid present; the amount of the 
latter may be estimated by comparison with solutions of known strength. 
. 4 4 R D. Crowell®) has worked out a process for estimating butyric acid in presence . 
of acetic and propionic acids basing mainly on the fact that the principal amount of 
th e butyric acid, besides some of the propionic acid, may be shaken out with petroleum - 
(| .P 150 to 300°) from the mixture of acids after Saturation with calcium chloride 
and some potassium chloride. It would be oe the scope of the Report to deal 
rther with this rather complicated mietaed. 
4 aes. Amer. chem. Soc. 39 (1917), 731; Journ. chem. Boe. 112 (1917), I]. 277. — 7%) Journ. Amer. chem. 
on 746; Journ. chem. Soc. 112 (1917), Il. 277. — %) Analyst 42 (1917), 133; Journ. chem. Soc. 112° 
, Ul. 277. — *).J. Biol. Chem. 29 (1917), 199; Journ. chem. Soc. 112 (1917), I. 278. — 5) Ann. Chim. 
yt. t- appl. 23 ea 27; Chem. Zentralbl. 1918, 1. 1073. —' 8) Journ. Amer. chem. Soc. 40 (1918), 453. 
ross hae, ie aS at Os a, Ae iy ia nil Ske y 
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