Part 98

Arsenic stock requires the following materials ready to hand before starting: Pounds. Caustic soda 4 White arsenic 10 Sal-soda crystals 10

There should be also some means for heating the solution in case, as sometimes happens because of impure materials, lack of skill, or some unforeseen circumstance, the heat created by mixing the materials should be insufficient to dissolve all the arsenic.

In a 5-gallon kettle or metal pail place the 4 pounds of caustic soda, add 1 gallon of cold water, and stir with a stick until the caustic soda is practically all dissolved. Without delay begin adding the white arsenic, in portions of a pound or two at a time, as fast as it can be dissolved without causing the solution to boil, stirring all the time. If the liquid begins to boil, stop stirring and let it cool slightly before adding more arsenic. The secret of success is to work the arsenic in fast enough to keep the solution very hot--nearly but not quite at the boiling point. The result should be a clear solution, except for dirt. If the liquid persistently remains muddy or milky, it may be because the operation has been conducted so fast that much water has been boiled out and sodium arsenite is beginning to crystallize, so add another gallon of water and stir. If the solution does not then clear up, the caustic soda must have been very low grade, and the undissolved substance must be arsenic. In that case, put the kettle over the fire, heat nearly, but not quite, to boiling, and stir. As soon as the solution of arsenic is complete, dilute to about 4 gallons, add the sodium carbonate, and stir until dissolved.

Cautions.--It is necessary to avoid splashing. Hence never work hurriedly; stir deliberately and regularly; do not dump in the arsenic and sal soda, but carefully slide them in from a grocer's scoop held close to the side of the pail and to the surface of the liquid. Perform the whole operation in a well-ventilated place and avoid inhaling steam.

After the solution has become cold add water to make it to exactly 5 gallons, mix well, let settle, and draw off into containers which can be tightly corked or otherwise closed. Jugs or demijohns are best, but tin cans will serve if occasionally inspected for leaks which may occur after a time through the action of the solution upon the solder of the can.

Tar stock is prepared thus: In a large metal pail dissolve three-fourths of a pound of caustic soda in 1 quart of water, add 1 gallon of pine tar, and stir thoroughly with a wooden paddle until the mixture, which at first looks streaked and muddy, brightens to a uniform, thick fluid somewhat resembling molasses. Test it by letting about a teaspoonful drip from the paddle into a glass of water (a glass fruit jar or a wide-mouth bottle will do) and stirring thoroughly with a sliver of wood. It should mix perfectly with the water. Globules of tar which can be seen by looking at the glass from underneath and which can not be blended with the water by repeated stirring indicate that more caustic-soda solution is needed. In that case make up more caustic-soda solution of the same strength and add it, not more than a pint at a time, with thorough stirring, until the desired effect is produced.

If an appropriate glass vessel for making the test is not at hand, take a little of the mixture between the fingers, then dip the fingers under water and try to rub off the tar. It should leave the fingers perfectly clean after a little rubbing with water. If an oily coating remains, more caustic-soda solution is needed. Such an extra addition of caustic soda will be required only in case of a very low-grade chemical or a very highly acid tar. The tar stock should be kept in closed containers, such as a pail with a friction top.

The quantity of S-B arsenic stock or of tar stock made in one operation can be varied as desired, provided the above-given proportions of the ingredients are adhered to. But one should attempt to work the S-B formula on a larger scale only after skill and experience have been acquired.

The boiled dip is less convenient than the S-B dip, but the final composition and effect of dipping baths prepared from the two are the same.

To make a 500-gallon bath provide:

Sal-soda crystals 24 pounds. White arsenic 8 pounds. Pine tar 1 gallon.

Put 25 gallons of water into a kettle or tank of from 40 to 50 gallons' capacity, heat to boiling, and add the sal soda. When this has dissolved add the white arsenic, then boil and stir for 15 minutes or longer, until the white arsenic has entirely disappeared. If intended for immediate use cool to 140∞ F. (by addition of cold water if desired), then pour in the pine tar in a thin stream while constantly and vigorously stirring the solution. Immediately empty the liquid into the dipping vat, which has already been three-fourths filled with water, and stir thoroughly.

All the utensils must be free from greasy or oily matter which would coat the arsenic and hinder its solution. The operation of boiling requires constant attention to avoid loss by foaming. Hard water may be used, but in that case considerable undissolved material, which, however, does not contain any arsenic, may be left after boiling.

For a stock solution to be kept on hand and used when needed add no tar, but after the solution has become cold make it up to 25 gallons, stir well, let settle, and draw off into containers which can be well closed. In this case the tar stock previously described is also required.

Diluting the dip.--First run water into the vat about three-fourths up to the dipping line, at which its capacity must be known. If tar stock is to be used the necessary amount will be one-third of a gallon for every 100 gallons of vat capacity. Measure it out, mix it with 2 or 3 times its volume of water and pour it along the surface of the water in the vat, stirring a little.

Every 100 gallons of standard-strength bath calls for 1-3/5 pounds white arsenic, which quantity is contained in four-fifths of a gallon of S-B stock or in 5 gallons of boiled stock. From these figures the quantity of arsenic or stock needed to charge the vat may be calculated. Or one may base the calculation on the following facts:

One pound of white arsenic will make 62-1/2 gallons of bath. One gallon of S-B stock will make 125 gallons of bath. One gallon of boiled arsenic stock will make 20 gallons of bath.

All solutions of arsenic are considerably heavier than water and if carelessly put into the vat they may plunge to the bottom and be difficult to mix. Therefore always pour the arsenic stock or a proprietary dip in a thin stream evenly along the vat except at the shallow exit end. Another precaution to be taken in handling proprietary dips is never to mix them first with small quantities of water, which may "break" them. Pour them directly into the water in the vat.

Finally, add water up to the dipping line and stir well. An excellent way to stir is by a pail tied to a rope. Sink it at the entrance end of the vat and haul it along the bottom to the exit. Then raise it, throw it back to the entrance end, and haul through again, repeating as many times as necessary but always hauling through in the same direction.

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.

Composition of dipping baths.

+-----------+------------------------------+ | Actual | Per 100 gallons of bath. | | arsenious +------------------------------+ | oxid. | White | S-B | Boiled | | | arsenic. | stock. | stock. | +-----------+----------+---------+---------+ | Per cent. | Pounds. | Gallons.| Gallons.| | 0.05 | 0.42 | 0.21 | 1.3 | | .06 | .50 | .25 | 1.6 | | .07 | .58 | .29 | 1.8 | | .08 | .66 | .33 | 2.1 | | .09 | .75 | .38 | 2.3 | | .10 | .83 | .42 | 2.6 | | .11 | .91 | .46 | 2.8 | | .12 | 1.00 | .50 | 3.1 | | .13 | 1.08 | .54 | 3.4 | | .14 | 1.16 | .58 | 3.6 | | .15 | 1.25 | .63 | 3.9 | | .16 | 1.33 | .67 | 4.2 | | .17 | 1.41 | .71 | 4.4 | | .18 | 1.49 | .75 | 4.7 | | .19 | 1.58 | .79 | 4.9 | | .20 | 1.66 | .83 | ... | | .21 | 1.74 | .87 | ... | | .22 | 1.83 | .92 | ... | | .23 | 1.91 | .96 | ... | | .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.