LIME WASH AS A DISINFECTANT.

Manawatu Herald, Volume XXX, Issue 3783, 30 January 1908, Page 4

LIME WASH AS A DISINFECTANT.

Writes a correspondent of the Farmers’ • Union Advocate: — “From almost time immemorial, lime wash has been considered by the farming community a highly satisfactory disinfectant for loose boxes, cowsheds, stables, etc., although doubts have been cast upon its efficacy from time to time, and many authorities, including our own Chief Veterinarian, have usually urged the addition of a large percentage of crude carbolic acid or other disinfectant of a chemical nature, holding that the chief value of, the lime wash lay in the fact that the person applying it and the paying for the disinfecting, could both see whether the work had been thoroughly accomplished. Recently during a series of experiments on the .values of various dfsimftctants, conducted by Dr Mcßride, of the Bureau of Animal Industry, Washington, U.9.A., the rather peculiar fact hail been brought to light that not only is limewash a poor disinfectant, but that carbolic acid itself when mixed with limewash, loses to some extent its germ - killing efficiency. The regulations of the Department of Agriculture recommend for the disinfection of trucks, pens, etc,, the following mixture :—Lime, i^lbsj

carbolic acid water 1 gallon ; or, in other words, per cent, of carbolic acid added to the lime wash as ordinarily used, and this led to its Value being put to experimental test; Dr. Mcßride’s experiments demonstrate a. percentage of carbolic acid, Which kills such a microbe as the staphylococcus pyogenes (one of the pusproducing germs) when mixed with ordinary water in 7 minutes, failed to do so in twice the time when mixed with lima wash. Similarly with tbe baccilus of swine fever, which, though killed in less than 2 x /z minutes with one part of carbolic in 123 of water, survived over double the time when treated with the same percentage of carbolic acid in lime wash- The reason of all this is that a part of the carbolic acid combines with the lime, forming carbolate of calcium, which “has a weaker disinfecting power than the acid, though of course much stronger than the acid alone. These experiments show that not only does lime require the addition of a chemical disinfectant, but that the solution requires to be stronger than if water alone be used, at all events with an acid disinfectant like carbolic.”