Phi I ips PW9790 narticulates on a continuous basis. (mass concentration

Phi lips new particulate monitor, PW9790. measures mass con- centration in pgr/m3. Provides real time in- formation on schedule: Y2 hr, 1 hr, etc., as you require. Total loading or respirable fraction measurement. Dynamic calibration provided via a mass standard. No weighing of filter papers. No zero drift. Field effective, PW9790 measurements are based on beta absorp- tion technique widely used in industrial application. Expect a new level of effec- tiveness in environmental quality management when you talk to Philips. Call today (91 4-664-4500) or write for full data on the PW9790 Particulate Monitor.

in /~gr /m~)

A North American Phil ips Co 750 South Fulton Avenue Mount Vernon NY 10550

CIRCLE 10 ON READER SERVICE CARD

LETTERS Jobs, jobs, jobs

Dear Sir: In the article, “Where Will the Jobs Be?” (€SAT, September 1975, p 806) you mention on page 812 sources of information on graduate pro- grams in Environmental Engineering. Another reference is the Register of En- vironmental Engineering Graduate Pro- grams. It is available from: Dr. Joe Mali- na, Director of Environmental Health Eng., 305 Eng. Labs.. Bldg., University of Texas, Austin, Tex. 78712.

A similar volume covering undergrad- uate programs is being edited now. For more information contact: Donald B. Aulenbach, Ph.D., Chairman, Subcom- mittee on Undergraduate Environmental Engineering Education, Rensselaer Poly- technic Institute, Troy, N.Y. 12181. [5 18-270-65531. John H. Austin Clemson University Clemson. S.C. 29631

Car emissions ti fuel economy Dear Sir: We at the Environmental

Activities Staff of General Motors were happy to see E. S. Starkman’s article on automotive emission control and fuel economy (€SAT, September 1975, p 820). An error appeared, however, in Figure 6 on page 824 in which three of the curves charting HC emissions against spark advance are reversed. Al- though the careful reader can detect the presence of the error quite easily, he would not be able to tell how the curves should be placed. Fred W. Bowditch General Motors Corp. Warren, Mich. 48090

Ed: The corrected chart is reprinted below.

F I G U i i i d

Emission and economy tradeoffs at 55 mph road load condition (Numberron curvesgive percent EGR)

JOIN THE AMERICAN CHEMICAL SOCIETY

American Chemical Society members receive Chemical and Engineering News each week. C&E News brings you the up-to-date happenings in the chemical world plus official ACS news.

AND THERE ARE MANY OTHER BENEFITS:

Publications- Members enjoy sub- stantial savings on world renowned ACS publications. Meetings-Two national meetings each year plus a host of regional and local meetings are held for your benefit. Local Sections-provide you with activities of local interest and an op- portunity to participate in Society affairs. Divisions- 28 subject divisions help you keep upwith yourspecial chemical interest. Educational Activities- short courses, audio courses and interaction courses help you expand as a professional. Employment Aids-give you a helping hand in today’s tight job market. But most important, your membership helps support the scientific and edu- cational society that represents you as a professional. 110,000 Chemists and Chemical Engi- neers know the value of ACS member- ship. Send coupon below today for an application. ~ ~ ~ - - - - - ~ -

American Chemical Society 7 Office of Member Services 1 1155 Sixteenth Street, N.W. Washington, D. C. 20036 I

Yes, I am interested in membership in the American Chemical Society. Please send information and application. I

1

I I

J Zip ~ ~ ~ - - - ~ ~ - - - Volume 9, Number 13, December 1975 1103