Mr. R. D. Anderson, - 2 November 26, 1959.
to preserve new smoke by dilution and thus prevent its agglomeration,
showed that the average particle size of new cigarette smoke is much
smaller than was previously thought. A value was obtained for mass
mean diameter of 0.2,zi as opposed to 0.92,4@ for undiluted smoke, and
2.0,44 for undiluted smoke aged 2 minutes. Your findings, then, are
consistent with this picture of smaller smoke particles.
With best regards,
Yours sincerely,
L. C. Laporte - MANAGER
RESEARCH AND DEVELOPMENT
R5V /FF
C)o
BATCo document for Province of British Columbia 21 April 1999

AIR MAIL
CA.L. 400111.0: "ATHLfTE TIMEPHOW9. WIELLPPOOTOM 2-6161
IMPERIAL TOBACCO COMPANY OF CANADA, LIMITED
3810 sr. ANTOINE STREET
0
M NTREAL 30
r 0, no,
-Nb, ember 26, 1959.
Mr. H. D. Anderson, .......
Research & Development Establishment,
British-American Tobacco Co. Ltd., ...............
Regentrs Park Road,
Southamptonj England.
Dear Hugh:
In reply to your letter of October 20),, we do not see how it
would be possible to Aform. K-38 9 into a filter plug. The K-389 is a
very finely divided powder, fibrous-rather than granular. The fibres
are curled, a few microns in length and a fraction of a micron in
diameter. When compressed, the material forms a hard cake rather than
a loose coherent mass and to act as a filter it must be supported by
some other material such as tobacco.
You consider it likely that since a mixture of K-389 (4%)
and tobacco has about the same coefficient of retention as does
tobacco alone (about 4.0), the retention coefficient of K-389 is also
of the same order. We have no other information on this matter, and
have wondered whether you have any experimental evidence that the
retention coefficient of a mixture is additive with respect to the
retention coefficients of the individual components. We would be very
hesitant to draw such a conclusion on the basis of our work since K-389
was present in the mixture to the extent of only 4%, and its coefficient
of retention could in actual fact be appreciably different from 4, yet
have an immeasurable influence on the coefficient of the mixture.
Unfortunately we do not see how we can make a filter from 100% K-389 to
prove this point.
low- With regard to the question of the retention coefficient
-lepending on air velocity, and increasing at low velocities, It is well
known (Handbook on Aerosols, U. S. Atomic Energy Commi@sion, 1950) that
imall particles are removed more effectively by a filter at low velocities
by the process of diffusion, whereas large particles are best removed at
high velocities by inertial deposition. It has been suggested that at
particles sizes around 1,,q I velocity has little effect. Some work recattly
published by Philip Morris Inc., (Determination of Particle Size and
Electric Charge Distribution in Cigarette Smoke) by Holmes, Hardcastle,
Mitchell, Tobacco Science 3 148, 1959) in which great care was taken
2
BATCO document for Province of BritiSh ColUrnbia 21 April 1999