approved.
LETTERS
total organic carbon volatile organic carbon total carbon THE DOHRMANNm DC-50 ORGANIC ANALYZER makes all of these measurements accurately and rapidly. Based en proven, EPA approved'" methods, it avoids interferences and undesirable pyrolysis reactions that historically have resulted in significant errors. DIRECT READOUT: Four-digit presentation shows carbon content directly in mg/liter or ppm. No recorder needed! DIRECT MEASUREMENT: A single sample injection gives either OrganicCarbon or Total Carbon content directly, not by difference. INDEPENDENT MEASUREMENT: Volatile Organics are determined separately from Total Organics to aid in source identification. RELIABLE MEASUREMENTS: Determines important, lightweight volatiles such as low molecular weight alcohols and ketones, normally lost by acidification and sparging. FAST: 5 minutes per determination. ACCURATE: Repeatability of 1 mg/ liter or * 2 % . WIDE RANGE: 1 to 2,000 mg/liter (ppm) without dilution. PRICE: $7,875, including start-up assistance and operator training.
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A G E N C Y , WATER P R O G R A M S , Guidelines Establishing Test Procedures for Analysis of Pollutants. FEDERAL REGISTER Vol. 38, No. 199, Part 11, Oct. 16, 1973. For brochures, reprints, or dates and locations of seminars, contact: DOHRMANN DIVISION, 3240 Scott Blvd., Santa Clara, CA 95050. (408) 249-6000. Telex 346 395.
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Environmental Science & Technology
Air cleanup Dear Sir: I n the editorial (ES&T, June 1974, p 487), you state that this issue includes information on . . . "another [utility's experience] with fuel cleaning prior to its burning." This implies that information is included about a utility attempting to burn cleaned coal, a topic of intense interest. (Well-cleaned coal of very low sulfur and ash content may not be burnable without severe boiler tube coating problems. This has been tested briefly with rumored disastrous but unpublished results.) Yet I fail to find reference to this topic in the June issue beyond the report, page 510, on solvent-refined coal (which is not adequately tested by a utility and may require boiler redesign for use). I fear this topic remains uncertain or perhaps has been deferred to a subsequent issue. Your editorial policy of separating features from current research papers is excellent and extremely i m portant for topics that do not include original information but are of broad interest and of conflicting reasonable opinions. R. F. Stewart Bu Mines Morgantown, W . Va. 26505
Water pollution companies Dear Sir: Your special report, "Water Pollution Control Industry," (ES&T, Oct. 1974, p 882) contains a claim by Osmonics, Inc. of being the first company to promote reverse osmosis for industrial waste treatment. This is a gross misstatement that will mislead the readers of your fine magazine: Our Mill Division was operating pilot reverse osmosis equipment and discussing a production plant with vendors in 1968; Osmonics, Inc. was not even founded yet. An intensive wastewater reuse program has been incorporated in our mill process; included in this process is a production reverse osmosis plant built by the Fluid Sciences Division, Universal Oil Products Co. David C. Morris Green Bay Packaging, Inc. Green Bay, Wis. 54305
Solar energy correction Dear Sir: In the article entitled, "Plenty of energy out there in the sunshine," (ES&T, Nov. 1974, p 976) you stated that "a 28-V voltaic cell array costs $7000." This is not true. A 28-volt array could cost as little as $700 depending on the load requirements (amp hours). Solar arrays are manufactured to accommodate specific amp hour requirements and it is misleading to your readers to inform them that a 28-volt array costs $7000. I?. W. Willis, President Solar Power Corp. Braintree, Mass. 02184
Uproar about chlorine Dear Sir: The sudden tumultuous publicity around possible adverse effects of chlorine disinfection of water in my opinion is wide of the mark. One of the items in "Currents" (fS&T, Sept. 1974, p 781) was that EPA Administrator Train called on chlorine producers to give priority attention to supplying chlorine for water supply and wastewater disinfection. One month later EPA research director Robeck went on the warpath against the use of chlorine. He quoted from my publication in Water Treatment and Examination (Vol. 23, 1974, pp 234-243), that haloforms are produced during chlorination of humic substances in natural waters, and added that the World Health Organization (WHO) "lists" chloroform as a carcinogen. As far as we know the evidence is very slender, as according to WHO Expert Group IARC's Monograph: "On the Evaluation of Carcinogenic Risk of Chemicals on Man" (Vol. 1, 1972). It is based on only one report of experiments on too small a number of laboratory animals, carried out in 1945. It is a different thing, of course, whether we should continue to use our surface waters for disposing of waste. Consumers in our affluent society, including the environmental analyst, all sin wittingly or unwittingly. The author found by headspace analysis traces of trichloroethylene in samples of the Rivers Thames,
