34 



COMMENTS OF ANALYSTS. 



R. W. Hilts: The methods submitted for this work were adhered to with the excep- 

 tion that in the removal of color from samples 2 and 3 the portions were weighed out 

 into the 50 cc graduated, glass-stoppered flask, acidified as directed, and the piece of 

 fat-free woolen cloth added (about 1.5 inches square). After standing over night the 

 volume was completed with aldehyde-free alcohol, without removing the cloth. 



Preliminary tests of the samples were made against a series of standards, but all 

 final determinations were made by matching in tne colorimeter. Final comparisons 

 were always arranged so that the depths of tints compared were within 10 per cent, 

 generally less, of equal strength. 



Results reported are calculated from averages of four to five readings made in rapid 

 succession with columns of 40 mm and 30 mm, i. e., 8 to 10 readings. Comparisons on 

 the different depths of liquid gave concordant results. 



Color in samples 1 (turmeric) and 2 (Naphthol Yellow S) gave no trouble whatever in 

 comparisons. The samples are so highly diluted in the final determination that the 

 color does not interfere. On sample 3 (Naphthol Yellow S) considerably more of the 

 original liquid is present in the comparison tube, due to its lower citral content, and a 

 very slight modification of tint in depths of 40 mm was noticed. With depths of 30 

 mm there was no apparent difference and tints were matched with ease. Sample 4 

 (turmeric) behaved similarly to No. 3. In depths of 40 mm there was a slight differ- 

 ence of tint, because nearly 3.5 cc of the original liquid was present in the tube. This 

 slight difficulty disappeared in depths of 30 mm. Samples 2 and 3 were very satisfac- 

 torily decolorized by the treatment with the cloth. However, in so far as ease of 

 comparison is concerned this treatment seems superfluous if comparisons are made 

 with comparatively short columns of liquid, as above noted. 



A. W. Hansen: The operator could not see that the color interfered with the com- 

 parisons. 



W. L. Dubois: The comparisons were made in wide Nessler tubes graduated to 100 

 cc which were cooled to 15 in a large bath and for comparison placed in a tall beaker 

 containing water at 15 and around which was wrapped a piece of white paper, the 

 beaker being set on a white surface and lifted therefrom a few inches at the time of 

 reading. The color in samples 2 and 4 did not seem to interfere with the determina- 

 tions. The fuchsin sulphite solution when made as directed retained a slightly brown- 

 ish tint. The fuchsin, however, which we had available for the preparation of this 

 solution was not labeled c. p. and this possibly may have accounted for our failure to 

 get a perfectly colorless solution. 



C. L. Cook: None of the readings of any of the samples was interfered with by the 

 presence of the coloring matter used. It was found necessary to allow the fuchsin 

 solution to stand at least forty hours before a blank could be obtained with the aldehyde- 

 free alcohol we were able to distil. 



F. D. Merrill: Samples 1 and 4 colored with turmeric gave a color differing some- 

 what from the standard used in the determination of citral. In Nos. 2 and 3 colored 

 with Naphthol Yellow S less difficulty was experienced in matching colors with the 

 standards in the determination of citral when the original extract was used, but when 

 the sample was decolorized by either^method suggested it had a very different color 

 as compared with the standard used in citral determination, and great difficulty was 

 experienced in matching colors. 



R. S. Hiltner: The small amount of turmeric in samples No. 1 and No. 4 did not 

 interfere perceptibly with the color comparisons. 



Sample No. 2, when heated with hydrochloric acid and woolen cloth under reflux 

 condenser as directed, turned brown, apparently due to decomposition of citral. A 

 somewhat similar change took place with No. 3, but to a less degree. 



The same result was obtained on these two samples by simply acidifying with 

 hydrochloric acid and treating at once with fuchsin reagent as by allowing the acidified 

 solution to stand over night in contact with wool. 



I was unable to secure alcohol that would not respond to the fuchsin test for alde- 

 hyde, even after prolonged standing and heating with m-phenylene diamin 

 hydrochlorid. 



Besides the figures obtained by the trial method, Mr. Hiltner, of the Denver Food 

 Inspection Laboratory, submitted a set obtained by a method devised by himself 

 using metaphenylene diamin as a substitute for the fuchsin sulphite reagent. The 

 writer makes the following claims for the method: 



First. Since there is no color reaction with acetaldehyde, more correct results may 

 be secured in the analysis of commercial extracts. 



