536 Journal of the Department of Agriculture. 



THE DIPPING OF SHEEP IN SO-CALLED 

 CARBOLIC DIPS. 



The Risk that may attend the Practice. 



By AiiTHLK Stead, i».Sc., E-esearch Chemist, Giootfoiitein Scliool 

 of As'i'iciiltiire, Middelbiirg', Cape. 



[Being tlie substance of a {taper read by Mr. Stead at a meetinii of theTechnicnl Otticeis 

 Association, Grootfontein School of Agriculture, on the 13th February, 1919, together with 

 a note on the Physiological Action "of tlio Phenols, by Mr. P. J. J. Fourie, M.R.C.V.S., 

 Lecturer in Veterinary Science.] 



While sheep lariueis would uot seem to be in tlie habit of using this 

 type of dip for the eradication of scab, it seems clear that such pre- 

 parations are frequently used for the purpose of destroying keds, and 

 that not a few valua1)le sheep liave been killed in the process. 



The dips are sold as non-poisonous; while that designation may 

 be true under certain conditions, it is not so under others. 



The common name for these dips would seem to indicate that 

 they contain carbolic acid (viz., phenol, CgHsOH), but usually this 

 is not the case. Presumablj the name has arisen from the '^ disin- 

 fectant " odour they possess, or possibly they have been so named 

 because they are made from materials obtained in the course of the 

 extraction of carbolic acid from coal-tar. Perhaps, however, the most 

 likely derivation ot the common name arises from the fact that phenol 

 and creosols (these latter are higher members of a group of 

 compounds which is called the Phenol Group, because ot 

 the many chemical similarities that exist between members 

 of the group and phenol itself) have been in the past, 

 when in -admixture particularly, indiscriminately called 

 "carbolic acid." Thus on page 177 of Wynter Blyth's "Poisons, 

 their Effects and Detection," it is stated : " It must always be borne 

 in mind that, witli regard to statistics generally, the term * carbolic 

 acid ' is not used by coroners, juries, or medicttl men in a strictly 

 chemical sense, the term being made to include disinfecting fluids, 

 which are almost wholly composed of creosols, and contain scarcely 

 any phenol." 



There are very many kinds of these dips on tlie market, and 

 usually they are sold under proprietary names. The starting point 

 of a great many of them is the " creosote oil " fraction of coal-tar from 

 Avhich naphthaleue has been separated. This liquid contains creosols 

 and other phenols, together with some pyridin and a large proportion 

 of hydrocarbons, the composition and properties of many of which 

 are very little known. 



A much better name for these dips would be " coal-tar creosote 

 dips." 



