96 On Disinfectants. 



•\vitli tlarce gallons — a small pailful — of water ; this will give a 

 milky liquid. For some purj)oses a clear solution of chloride of limo 

 is useful ; this is produced by putting 2 ounces of chloride in 1 gallon 

 of water, and after shaking uji the milky liquid allowing it to settle, 

 and finally drawing off the clear watery liquid from the insoluble 

 lime deposit. 



Although chloride of lime is perhaps the most generally useful dis- 

 infecting agent, its extensive use in cowsheds or stables cannot be 

 recommended as long as stock are kept in them, for if spread about 

 in such abundance as to destroy contagion it is sure to injui-e the 

 health of cattle, or if used more sparingly its efficiency in destroying 

 the infectious matter will be doubtful, 



Chlorine gas is a still more powerful and concentrated disinfectant, 

 in a form which is convenient for certain purposes, such as the disin- 

 fection of cowsheds or the holds of cattle-sheds by fumigation. 

 Chlorine fumigations are made either by placing in a sloj)-basin or 

 deep jar finely powdered black oxide of manganese and pouring upon 

 it common muriatic acid ; or by mixing together 3 jiarts of common 

 salt, 1 part of black oxide of manganese, 2 parts of oil of vitriol, 

 diluted with an equal proportion of water. 



The mixtm-e of salt and manganese may be kept ready mixed for 

 use, and the diluted oil of vitriol pom'ed upon some of the mixture in 

 a shallow vessel when required. 



For fumigating a large cowshed about 1^ lb. of finely powdered 

 black oxide of manganese and It pint of muriatic acid ^^•ill be suffi- 

 cient. The heat generated by the oxide in acting upon the black 

 oxide of manganese disengages a good deal of chlorine ; but if it is 

 desired to obtain all the chlorine which the mixtiu-e is capable of 

 yielding, it is advisable to place the vessel in which the acid and 

 manganese are mixed together on a gentle charcoal fire. Another 

 plan of generating chlorine is to pour dilute sulphuric acid (1 part of 

 strong acid and 10 of water) upon chloride of lime. 



As chlorine is an extremely poisonous gas, the person who is about 

 to fumigate an unoccupied place must take care not to inhale any of 

 the gas. 



Stdjjliurous acid, which acts, not in the same, but in a similar 

 manner, may also be used for disinfecting piu'poses Avith very great 

 propriety, and it is very readily prepared. Light some flowers of 

 sulphur (about 1 or 1^ lb.) : the resulting gas is sulphiu'ous acid, a 

 most powerful destroyer of organic matter, which may be usefully 

 applied to parts of buildings not otherwise accessible to bleaching 

 powder or other disinfectants. 



Nitric and nitrous acids are powerful oxydising agents which destroy 

 organic matters by yielding to them oxygen in an active state. They 

 burn up, in fact, organic matters at a low temperature in a manner 

 similar to that in which fire destroys them at an elevated temi^erature. 

 Nitrous acid fumigations were introduced by Dr. Carmichael Smith, 

 who, in 1797, received a reward from Parliament of 6000Z. for the 

 publication of his formula. Nitric and nitrous acid vapoiu's may be 

 produced in the following manner : — 4 ozs. ^of powdered nitre are put 



