Page 158 - James Rodger Fleming - Fixing the sky

liquid and Solid Carbon dioxide

In 1891, Louis Gathman of Chicago obtained a patent to encourage and enhance
rainfall by chilling the atmosphere through the release of “liquefied carbonic
acid gas” shot from a projectile or released from a balloon. In Gathman’s plan,
the liquid carbonic acid sent into the clouds would vaporize and expand, chilling
the surrounding air. Even though one method involved delivery of the agent
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by artillery burst, Gathman’s idea was quite distinct from those of the concus-
sionists. Senator Charles Farwell (R-Illinois), who had supported Robert Dyren-
forth, was reportedly interested in the patent, but did not pursue the idea. Fer-
nando Sanford, a physics professor at Stanford University, praised Gathman’s
theory, since he thought that cooling the air was a physically sound technique to
enhance rainfall artificially. Sanford categorized Dyrenforth’s recent Texas rain-
making expedition as a “national fiasco,” since the explosions of the concussion-
ists actually heated the air and encouraged the proliferation of charlatans. Real
scientists conducted carefully controlled tests and were published in the tech-
nical literature; they did not petition Congress for money on the basis of their
brainstorms. Sanford wrote: “Unquestionably we have [in Gathman’s proposal]
the proper kind of an agent for producing rain. The only question to be con-
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sidered is one of finance.” Unfortunately, the scale of the atmosphere worked
against the idea. Sanford calculated that it would take an astronomical amount
of carbonic acid, 406 million pounds of it, to cool a cubic mile of air sufficiently
to generate a quarter of an inch of rainfall over 640 acres. With carbonic acid
selling for $1 a pound, Sanford estimated that the cost of the rainfall per acre was
a prohibitively expensive $600,000.
If Gathman had taken the next step, proposing the use of solid carbonic acid
(dry ice); if Sanford had seen a triggering effect to the cloud seeding rather than
a brute-force approach to chilling the entire atmosphere; and if someone had
actually tried the experiment, perhaps by shelling a growing cumulus congestus
cloud . . . but those are a lot of “ifs.” In 1948 the Stanford Law Review, in an exam-
ination of the science behind the current cloud-seeding rage, briefly mentioned
Gathman’s patent, pointing out that minute particles of dry ice and even artificial
clouds must have been formed in the rapid cooling process. They speculated that
if Gathman were alive, and if his patent had not long since expired, “he might
have an action for patent infringement against those who are using dry ice to
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cause rainfall.” Two more big “ifs.”
In the late nineteenth century, supercooled cloud conditions were known,
and meteorologists were hinting at the possibility that ice-phase processes could
initiate precipitation. In 1895 Alexander McAdie wrote that, by analogy, “a snow-

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