The standard-strength bath prepared as above contains practically 0.19 per cent arsenious oxid when fresh. After use oxidation may set in and weaken it, but it will not need to be strengthened so long as it tests not less than 0.175 per cent arsenious oxid.
To make up small quantities for spraying, to each 5 gallons of water measured out add first 2 fluid ounces (4 tablespoonfuls) of tar stock, and then 5-1/8 fluid ounces of S-B stock or 2-1/8 pints of boiled arsenic stock.
The standard strength of bath should be adhered to so far as possible because its effectiveness against ticks will effect eradication in the least time and with fewest dippings. But if time is not pressing it is sometimes best to begin with a lower strength, say 0.14 or 0.15 per cent, and gradually work up to full strength as the cattle become accustomed to the treatment. This is certainly a wise method for the individual cattle owner who is outside the area of cooperative work and who lacks aid and advice from experts. Weather conditions also need to be considered. Hot or moist weather is more trying to the cattle than cool or dry weather. The longer the time needed for the cattle to dry off after dipping, which of course primarily depends on the proportion of moisture in the air, the more liable they are to show blistering or other injury through the continued absorption of arsenic by the skin. The combination of heat and moisture is particularly bad, and under such conditions it may be desirable, unless other conditions prohibit, to use the bath somewhat weaker than standard strength. The following table shows the quantities of arsenic and stock solutions contained in 100 gallons of bath of different strengths, so that the quantities necessary to charge a vat of any size at any strength can be found by simple multiplication.
| Actual arsenious oxid. | Per 100 gallons of bath. | Actual arsenious oxid. | Per 100 gallons of bath. | ||||
|---|---|---|---|---|---|---|---|
| White arsenic. | S-B stock. | Boiled stock. | White arsenic. | S-B stock. | Boiled stock. | ||
| 0.05 | 0.42 | 0.21 | 1.3 | .15 | 1.25 | .63 | 3.9 |
| .06 | .50 | .25 | 1.6 | .16 | 1.33 | .67 | 4.2 |
| .07 | .58 | .29 | 1.8 | .17 | 1.41 | .71 | 4.4 |
| .08 | .66 | .33 | 2.1 | .18 | 1.49 | .75 | 4.7 |
| .09 | .75 | .38 | 2.3 | .19 | 1.58 | .79 | 4.9 |
| .10 | .83 | .42 | 2.6 | .20 | 1.66 | .83 | .......... |
| .11 | .91 | .46 | 2.8 | .21 | 1.74 | .87 | .......... |
| .12 | 1.00 | .50 | 3.1 | .22 | 1.83 | .92 | .......... |
| .13 | 1.08 | .54 | 3.4 | .23 | 1.91 | .96 | .......... |
| .14 | 1.16 | .58 | 3.6 | .24 | 2.00 | 1.00 | .......... |
As dipping goes on the bath naturally needs replenishing, and its strength probably needs correction from time to time. Full directions on these points may be found in Farmers' Bulletin 1057.
Prepared dips.—Proprietary arsenical cattle dips appear now to have passed the experimental stage and to have become established as reliable and useful products. At any rate this can be said of the brands which have received permission for use in official dipping in place of the homemade dip. The formulas and standard samples of all such brands are in possession of the Bureau of Animal Industry and the manufacturers are required to guarantee that their products as placed on the market will be kept up to standard and that all requirements of the bureau will be observed. Like the homemade dip they all contain sodium arsenite as the active tick-killing agent. They do not all contain pine tar, because that substance is difficult to blend into a highly concentrated product, but they all contain some other substance or mixture of substances of such character and in such quantity as field trials have proved will produce the same effects.
They are not regarded as any more effective or any milder on the cattle than properly prepared homemade dips. None the less they are undoubtedly safer for general use because they offer decidedly fewer opportunities for making mistakes in the quantities used or in the operations gone through and also fewer chances for accidental poisoning or other injury from the handling of powerful chemicals. Whether their higher cost is sufficiently outweighed by these considerations is necessarily a matter for individual decision.
Precautions in the use of arsenic and arsenical dips.—The fact that arsenic is a violent poison is what renders it valuable, for the fever tick is hard to kill. But, like a keen-edged tool, it may be decidedly dangerous if ignorantly or carelessly handled. Three possibilities of danger must be kept constantly in mind; danger to oneself, danger to other persons, danger to animals.
The dry, powdered white arsenic should be kept in a tightly covered pail, plainly labeled. Paper bags are unsafe because they easily burst, and arsenic so scattered about looks harmless enough. In weighing or otherwise handling the arsenic avoid raising dust or breathing it in, if raised, and keep it off the skin and clothing. In mixing or boiling stock solutions work only in a well-ventilated place, and on the windward side of the kettle so that steam arising from it will not be inhaled.
The stock solutions are in some respects more dangerous than the original substance because the arsenic in them is already in solution and can act very quickly. If any gets on the skin or clothing it must be washed off without delay. Cattle must be kept away from such solutions or from anything that has been in contact with them, for cattle craving salt have been poisoned by licking the outside of leaky barrels and by licking the earth around dipping vats where a little concentrate had been carelessly spilled in charging the vat. All such poisoned earth must be removed, buried, and replaced by fresh.