NOTES ON SCIENCE, MECHANICAL INVENTIONS, ETC.

New Zealand Herald, Volume XXVII, Issue 8162, 25 January 1890, Page 4 (Supplement)

NOTES ON SCIENCE, MECHANICAL INVENTIONS, ETC.

♦ — POISONING BY TINNED PROVISIONS. The British Consul at Baltimore, in a recent report on tinned goods deleterious to health, says that all tinned or canned provisions which are hermetically sealed are packed in tins made of tin-plate, or sheet iron superficially alloyed with tin. This is imported to the United States exclusively from Britain, as there are no tin-plate manufacturers in the former country. 130,000,000 cans are made every year in Baltimore alone ; and 2,000,0001b of solder are consumed in making them. Equal parts of block tin and lead form the best solder; but a baser kind composed of a larger proportion of lead is not uncommon. A flux of powdered resin, or a much more deleterious flux composed of chloride of ginc, containing free muriatic acid, is applied to the tin surface to be soldered ; atnd the unfortunate and dangerous practice to to apply this on the inside. The use of an acid flux for inside soldering is alleged to be a source of danger to health ; while the resin flux communicates its taste to the contents of the can. In France and Germany all tins containing articles of food are soldered on the outside ; and attempts have been made wholly to abolish inside soldering In the United States. But they have not yet been entirely successful. The first danger from the inside surface of solder is the direct solvent action of an acid fluid on the lead, when acid vegetables or fruit are preserved without syrup. The second source of danger is galvanic action. Some American sardines have a particularly evil reputation as at present put up. Professor Tonry, of Baltimore, writes of one of these sardine tins, soldered on the insjue, that fully a quarter of the interior surface of the metal was eaten away. The fish inthis tin were nearly all eaten by three persons, two of whom were children ; and all were taken 111 within half-an-hour — one child dying within twenty-four hours. A chemical examination of the viscera revealed lead, which was also found in the oil and in the remaining contents of the tin. The verdict at the coroner's inquest was that death resulted from lead poisoning from a sardine tin improperly soldered.