The Use of Hard or Saline Waters for Sheep Dipping. 43 



magnesium, or sodium salts in waters influence the solubility of the 

 dips more, and also whether it is the sulphate or the chloride of any 

 of these three elements that has the greater inhibiting effect. More- 

 over, as already pointed out, certain classes of dips may be seriously 

 affected — at least by some of the above salts — and otheis either not 

 at all, or else by otlier salts. What is needed, therefore, in order to 

 perfect such an investigation, is to correlate the waters of a particular 

 district with the class of dip to which they are best suited. 



Experience in the United States. 



Quite opportunely for the conditions in South Africa the United 

 States Department of Agriculture has recently issued, in Farmer's 

 Bulletin No. 798, on " The Sheep Tick," a warning against the use of 

 certain classes of sheep dips, particularly of the carbolic type, with 

 brak, alkali, or hard waters. It will undoubtedly be of advantage 

 to take over some of the cautions and advice there given. 



In the United States, as with us, hard or brak waters are found 

 more or less frequently in all parts, and, where it is possible to do so, 

 their use for dipping purposes should be avoided. 



When soft water is used for making* up a dip the mixture has 

 greater wetting* power than when some of the hard waters are used. 

 If the wetting power of a mixed dip is low the fluid has a tendency 

 to form small bead-like drops all over the wool instead of uniformly 

 covering the entire surface. If we increase the wetting power of 

 such a mixture we make it more efficient because we ensure the more 

 even distribution of the active principle and the maximum possible 

 wetting for all parts of the animal that are covered by the liquid. 

 Even good dips may become ineft'ective if they are made up with 

 alkali water. In this respect, then, the American experience confirms 

 our own. 



Before any coal-tar, creosote, cresol, or carbolic dip is mixed with 

 hard of alkali (brak) water, a test should be made to see whether such 

 admixture results in a permanently uniform fluid ; or whether a 

 separation between the liquids occurs, something like when oil and 

 water are shaken up and left to stand for a short while; or else, 

 .whether a soft semi-solid, or curdy precipitate or sediment settles 

 down. Such a test may be carried out by placing a measured quantity 

 of dip in a clean bottle or jar of clear glass and adding to this, mixing 

 thoroughly meanwhile, approximately the same pi'oportion of water 

 (preferably warm) that would be added to the dip in actual piactice. 

 If after standing for one hour the mixture is no longer uniform, tut 

 separates out in two layers — if, for instance, an oily layer or a mass 

 of globules appears either on the surface or at the bottom of the 

 mixture, that kind of water should be regarded as unfit for making 

 up the dip, at all events without further treatment. 



In some cases, however, it is impossible to get any other than 

 permanently hard waters for making- up dips. It is then necessary 

 to "break" the water by adding to it carbonate of soda in the pro- 

 portion of from 1 to 4 pounds of salt per 100 gallons of water, accord- 

 ing to the hardness of the latter. In bad cases, however, it would be 

 desirable to have the water analysed and obtain professional advice 

 on the best manner of correcting the water so as to render it suitable 

 for preparation of dipping mixtures. 



