a period of 15 minutes, the colored solution is measured in a suitable spectrophotometer at 520 mp. If the color is too intense, the basic aqueous extract is diluted to volume in a suitable volumetric flask with LON sodium hydroxide and a 2.0-ml. aliquot of the dilution is used for color development. Each day a reagent calibration should be done. This calibration is made by analyzing an HQ-free MEHQ standard solution directly by using the 4-aminoantipyrine procedure. RESULTS
Using the above described procedures, the results in Table I were obtained. I n all cases, a I-em. path length spectrophotometric cell was used with the reference solvent being water. The per cent recovery is based on the respective calibration for each particular day of analysis. DISCUSSION
The amount of eluate collected, between 30 and 60 ml., does not affect the per cent recovery. This was demonstrated hy running three standard solutions, 72.8 p.p.m. MEHQ, through
respective columns, and then collecting 30, 45, and 60 ml. of eluate. Upon analysis of each elute, we found that the per cent recovery for each sample was between84 to 86%. Since we are interested in the general field of acrylics, we scouted the feasibility of extending this technique to a methacrylate and another acrylate. During the analysis of a methacrylate sample, we found that the basic extract of the eluate exhibited the benzoquinone color. This indicates that either the column was not resolving properly or there was an incomplete conversion of HQ to benzoquinone due to an insufficient supply of oxygen. Apparently, the latter alternative is the case since a satisfactory separation is achieved by bubbling oxygen through the preliminary basic extraction of the monomer. Therefore, for systems other than ethyl acrylate (EA), it may he necessary to ensure complete conversion by the addition of oxygen to the preliminary extraction. Several samples of methyl acrylate (MA) which contained known amounts of MEHQ and 2000 p.p.m. HQ were
also analyzed. However, we were able to recover only about 50'% of the phenol. When a standard solution of MEHQ in MA, which was free of HQ, was analyzed directly without the column separation, about 65% of the phenol was recovered. Apparently, the base is consumed by hydrolysis of the ester and as a result only a portion of the phenol is extracted. During the extraction, we noticed that the volume of the monomer layer had decreased. We were able to alleviate this problem by diluting 1 part of MA with 4 parts of uninhibited EA. Several standards were run directly and in each case 100% recovery was achieved. Since the system is essentially EA, we have reason to assume the HQ can be effectively removed by the partitioning column. Also, the loss in sensitivity due to dilution can he re-established by using &em. cells instead of I-cm. cells. LITERATURE CITED
(1) Lacosta, R. J., Venablc, S. H., Stone, J. C., ANAL.CHEM.31,1246 (1959).
JACKC. STOXE Rohm & Haas Co. Philadelphia, Pa.
The Determination of Fine Metallic Filament Morphology by Ultramicrotomy Warren K. Tice and William R. Lasko, United Aircraft Corp., Research Laboratories, East Hartford, Conn. ULTRAMICROTOME has proved to be a valuable tool in cutting thin metal foils from both single and multiphase materials, However, these studies have been restricted to obtaining sections of continuous systems of metals and alloys. Application of ultramicrot-
TEE
omy recently has been made at these laboratories in which the size, cont i u i t y , and distribution of synthetically-encased filaments of lead in a matrix of aluminum or copper in wire form could be determined without severe deformation.
'.
Figure Micrograph Of Cu-Pb wire made reflected-'igh+ microscopy 1500X
Microscopy by reflected light was applied initially to the study of relatively large diameter (2 microns) lead filaments encased in 0.71-mm. diameter copper wire. A section of a typical drawn copper wire which contained 500 lead filaments is shown in Figure 1. However, as refinements were made in the wire-drawing process, the filament diameters were reduced and any further attempts at utiliaing the light technique proved unsuccessful. Replicas for electron metallography also were unsatisfactory, as shown by the micrograph in Figure 2. I n this instance, a negative carbon-platinum replica was prepared of a polished and etched aluminum wire (0.18 mm. in diameter) containing 2500 fine lead filaments. NO information concerning the morphology of the individual filaments could be gained by this method, as shown by the arrow, although, some background structure in the aluminum matrix is evident. This approach is largely ineffective because of reaction products formed during etching and smearing of the fine lead filaments into a mass during polishing. VOL. 35, NO. 10, SEPTEMBER 1963
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