US1502174A - Fumigant - Google Patents

Description

Patented July 22,1924.

un ts!) STATES P Improvements in Fumigants, of which the following is a specification.

This invention relates to an improved fumigant which overcomes the disadvantages.

of many of the present fumigants and offers additional advantages. flhb term fumigant is employed in a generic sense to include substances employed to destroy or kill bacteria, insect and animal life and fungus growths, etc. a

Among the substances generally used was carbon disulphide but the great fire hazard attendant upon its use has caused its use to be forbidden by boards of underwriters. Resort has been had to hydrocyanic acid gas.

This is a highly toxic gas, insidious and rapid in effect but it is odorless, tasteless, invisible and unfortunate losses of human lives have resulted from its use. Further, this last-mentioned gas is lighter than air and is thereforeextremely difiicult to apply and rect'to the work in hand. In the employment of fumigants, the practical problem as distinguished from the theoretical is usually to fumigate an enclosure whether box, room, barn, house, etc., and, as is well-known, such enclosures are pervious and the fumigant in gaseous form seeps away or leaks beforethe gas is concentrated to the required toxicity.

. This is particularly true of the toxics of higher volatilities. This invention provides ,a fumigant which offers the desired degree of volatility with the necessary toxicity.

The object therefore of the invention is to provide an improved fumigant.

Other objects of the invention will more fully appear from the following description and will be pointed out in the annexed claims.

This novel fumigant comprises a combination of chloropicrin (CCl NO and carbon tetrachloride (GU1 The chloropicrin was developed for war purposes and was primarily adapted for the repelling of human beings.- It may be made or obtained in liquid form and is of fair volatility but is not volatile enough for use eifectively as a fumi:

gant because it volatilizes at such a relatively slow rate that the usual leakage prevents the desirable concentration of the toxic gas within an enclosure to be fumigated. In

N. Crmrnmri a.

tron, too long a tlme 1s requlred for the neo- ENT OFFICE.

"Yhnnonron CHAPMAN, or ST. PAUL, MINNESOTA.

' FUMIGAN'I';

15, 1923. Serial-N0. 681,009.

practice, even if the averagerate of leakage v is somewhat less than the rate-of volatilizeessfary fumigating concentration; while, if the leakage rate is the greater, the-necessary concentration can not be built up. Extensive research and practical tests showed the practical disadvantages of many other substances. Among them was carbon tetrachloride which is obtainable in liquid form and is at present used in what are known comnercially asfire extinguishers. This is- 'a iquid whose relative volatility is very high and whose toxicity is relatively low. Hence,

this substance was not available as a practical fumigant because, while the desired concentration might be obtained, the toxicity was not great enough. It has been found that a physical mixture of these two liquids in proper proportions produces a fumigant offering the advantages sought and lacking in the disadvantages of each, individually. The preferable proportions are half and half. As they are substantially equal in units of weight or volume, it is believed to be relatively immaterial which basis is used although itis convenient to designate equal parts by volume. So far as can be deterinined there is no chemical reaction between these substances yet, this novel compound is similar to carbon-tetrachloride in its volatility and similar to chloropicrin in its toxicity. In other words, a fumigant is provided which substantially has the toxic attribute of chloropicrin and the volatility attribute of carbontetrachloride. Furthermore, the presence of the carbontetrachloride adds its well-known quality of an-active fire-extinguishing agent so that the novel fumigant is acceptable to the fire underwriters. This novel fumigant, it may be- 2. A fumigant comprising carbontetra ,chloride and chloropicrin in equal partsby volume.

In witness whereof, I havehereunto set my hand this fifth day ofDecember 1923.

ROYAL NORTOK CHAPMAN.