6j| Mr King's description of a New Safety-Tuhe. 



best possible situation to be impregnated with the gas, readily 

 absorbs it, but is rendered useless by the admixture of foreign 

 ingredients from the retort. This inconvenience, however, is 

 obviated by the safety-tube of Welther, which is also objec- 

 tionable from its necessarily delicate construction, and its un- 

 manageable length, even when a moderate degree of pressure 

 is required. Various plans have from time to time been adopt- 

 ed to overcome these inconveniences. The most successful is 

 that proposed by the late Dr Murray, who suggested the for- 

 mation of a globe on the long leg of each tube of communica- 

 tion, a little above their insertion into the bottles. This plan, 

 too, has its defects. The bent tube cannot with safety be 

 made to dip among more fluid than is barely sufficient to fill 

 the small globe on its leg. A greater number of bottles is 

 therefore necessary to bring the same quantity of liquid in 

 contact with the gas. There is also considerable waste of the 

 aeriform fluid in the spaces of the bottles not occupied by the 

 liquid; an increased number of bottles multiply the luted joints, 

 and the risk of leakage is consequently augmented. 



By the use of the safety-tube, of which I have sent you a 

 drawing, any degree of pressure may be applied that the 

 bottles can resist, and which may be regulated at pleasure 

 without altering its length. Neither is it necessary for its ac- 

 tion that the first bottle contain liquid ; the others may be 

 filled almost completely ; it may be ground with ease air-tight 

 without lute ; it is not liable to derangement ; is easily ad- 

 justed ; allows egress of the gas, when necessary, to prevent 

 explosion, and ingress of air in the event of a partial vacuum 

 being formed at the conclusion of the process. Such are the 

 advantages of this little piece of apparatus, the construction 

 of which occurred to me some little time ago ; and I have 

 since, on trial, found it very useful. As I have not seen the 

 same on record, I now transmit you this notice, which, 

 through the medium of your widely circulated Journal^ may 

 be of advantage to the manufacturers of muriatic acid, &c. or 

 to the experimental chemists in Europe. I go*^^ it made at the 

 extensive flint-glass manufactory of Messrs Bailey and Com- 

 pany, Edinburgh, whose facilities for the manufacture of all 

 glass-articles are the best in Scotland. I ought to have writ- 



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