SOME ASPECTS OF THE SAFETY OF AEROSOL CONTAINERS 383 near foodstuffs. Similarly, dispensers containing a product liable to be offensive if released, are restricted relative to living quarters and stowage of foodstuffs. Where it has been shown, following the tests described, that a protective cap is unsatisfactory, it is usually recommended that strong dividers and/or layer pads be provided within the inner carton and, if the spray that would be discharged is especially hazardous, an outer wooden case be used. If a cap is found to be particularly unsuitable, it is suggested that alternative designs be considered. For the carriage of aerosol dispensers by Inland Mails, the G.P.O. have their own regulations and approve suitable packings. It is in connection with Overseas Mails that the advice of this Laboratory is sought. Once a mail bag has been sealed, there can be no knowledge or indication of the potentially hazardous nature of the contents, nor can other than general stowage precautions for P.O. mails be taken. Whilst the number of dis- pensers carried in this way will, of necessity, be relatively small, there may be a possibility of a fire from leakage in a mail bag--and fire in a ship or aircraft can be a very much more serious matter than in terrestrial storage. In these circumstances, only the most innocuous formulations are likely to be accepted as anonymous freight. The I.A.T.A. regulations for the carriage by air of "restricted articles" require classification of aerosol sprays according to the hazardous nature of the contents in some cases of doubt as to the correct classification, products have been examined in this Laboratory and the Ministry of Aviation advised. The extremes of temperature (quoted earlier in this paper) anticipated in flight and in ground storage are not more extensive than those considered for carriage by sea. In the unpressurized holds of some older types of cargo aircraft, and possibly some future jet transport, the pressure differential at 35,000' would be about 0.75 atm, whilst in high flying aircraft that have been pressurized (to the equivalent of 8,000'), an accident resulting in explosive decompression would cause a fall in pressure of 0'5 atm. In practice, all containers for liquid "restricted articles" are required to withstand at least 1 arm and where aerosol products have been pressurized to 2.7 arm at 21 ø and/or 7.1 atm at 55 ø, the regulations for compressed gases shall apply" (p.C:•). ACKNOWLEDGEMENTS The experimental work described has been undertaken as part of the analytical and advisory services offered by this Laboratory to other (U.K.) Government Departments. Acknowledgement is made to Mr. M. J. Glover, for experimental assistance and helpful discussions. (Received: 2$th February 1963)

384 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS REFERENCES The Carriage of Dangerous Goods and Explosives in Ships Report of Ministry of Trans- port Standing Advisory Committee, London (1957) 5th Amendment (August 1962) (H.M. Stationery Office, London) I. zt.T. zt. Regulations relating to the carriage of Restricted Articles by Air 8th Edn. (April 1963) Herzka, A. Soap Perfumery • Cosmetics $0 813 (1957) 4Herzka, A. and Pickthall, J. Pressurized Packaging (Aerosols) 2nd Edn. (1961) (Butterworths, London) CPO (FS) Specification No. M-oe-9/8 (January 1963) Draft Report of the Home 0l•ce Gas Cylinders and Containers Committee (1961) Holler, E. Symposium on Meteorology of Ships' Cargo Spaces (June 1956) (Hamburg) Aerosol Guide 11 (1957) (C.S.M.A., New York) Lester, D. and Greenberg, L.A. Arch. Ind. Hyg. Occupational Med. 2 335 (1950) Soap Chem. Specialties $7 133 (November 1961) Jones, G. W. and Scott, F.E. Report RI $908 (1946) (U.S. Bureau of Mines) Soap Chem. Specialties $8 142 (January 1962) Reed, W.H. ibid $2 197 (May 1956) Scott, R.J. Aerosol Age 7 18 (January 1962) Scott, R. J. and Feathers, R.E. Soap Chem. Specialties $8 154 (June 1962) Compton, C.C. ibid 72 (November 1962) DISCUSSION 3/[•. C. Broo•: Do you consider there to be any special hazards in handl- ing dispensers which have been leak-tested at 55øC ? For example, what would be the effect of accidentally dropping a dispenser onto the floor as it is being withdrawn from the water bath ? TSE LEC•U•E•: I have no specific experience on this point. I may make a few observations, however. Hydraulic tests on untilled containers constitute purely internal pressure tests of the effectiveness of seams and crimping of the container. During hot storage testing, filled dispensers suffer two constraints: An internal pressure due to increase in vapour pressure of the contents and, additionally, heat may cause a weakening of the structure of built-up containers. We have found that when 12 oz (and larger) filled containers have been dropped on to an unyielding surface, from say 6 ft, there is usually some slight dirnpling of the dished base though not usually complete inversion to the domed conformation. This dimpling may be due to the liquid contents having a separate momentum from that of the con- tainer. If motion of the liquid in the contrary direction is inhibited by the pressure in the overlying vapour space, raising that pressure by increasing the temperature presumably reduces hydrauhc transmission of the shock, which would increase the strain on the base. This is quite conjectural because I have no direct experimental evidence of this. D•. H. K[•E•: Does the toxicity information given in Table 4 refer to a 50% or a 100% lethal dose ? What is the source of this information ? What is the number of the patent dated 1889 which refers to ethyl chloride?