12 BULLETIN 230, U. S. DEPARTMENT OF AGRICULTURE. 
brush or a stiff bristles brush. It will be impossible to obtain a water- 
tight coating if it is applied while water is seeping through the wall. 
It will be well to wait for the dry season, when the ground water is 
reduced to its lowest level, before attempting to waterproof by plas- 
tering. Should water appear to be coming through a well-defined 
crack in the wall, calking with oakum or cotton may be resorted to in 
order to stop the leakage until a plaster coat of oil-mixed mortar can be 
applied. It will be necessary to mix the mortar for plastering to a 
rather dry consistency, and it should be troweled hard in order to 
obtain a hard, dense waterproof surface. A wash of cement and water 
mixed to the consistency of thick cream and applied before the oil- 
mixed mortar coat is put on will aid the new mortar in adhering to the 
old work. The old wall must be thoroughly wet before the new 
mortar coat is applied. 
WATERING TROUGHS. 
The use of oil-mixed concrete in the construction of watering 
troughs will be found to give excellent results in maintaining them 
in an absolutely water-tight condition. 
For this purpose a mixture of 1 part of Portland cement, 2 parts 
of clean coarse sand, and 4 parts of gravel ranging in size from \ 
inch to 1 inch is recommended. The mixture should likewise con- 
tain 10 per cent of oil based on the weight of cement and should 
be mixed to a jellylike consistency. It will be well to provide wire- 
mesh or steel-rod reinforcement for the bottom and walls. Care 
should be taken to puddle the concrete into place thoroughly and to 
trowel or spade the material next to the molds. This flushes the 
mortar to the surface, making it smooth and dense, and rendering a 
finishing coat of plaster unnecessary. Should a very smooth surface 
be desired, an effective finish may be obtained by applying several 
paint coats of oil-mixed cement grout made as follows: Enough 
water should be mixed with cement to form a paste of soft, putty- 
like consistency. To this paste should be added 3 per cent of oil, 
based on the weight of dry cement in the mixture (a 10-quart bucket 
of dry cement requires about a pint of oil for this purpose), and 
the whole should be mixed until the oil is entirely combined with the 
other ingredients. The paste may now be thinned down with more 
water to the consistency of cream, after which it may be applied with 
a stiff brush to the previously dampened concrete. A second coat of 
this oil grout should be applied after the first coat has hardened. 
Care should be taken that it does not dry out too quickly by applying 
it to the dry concrete or exposing it to the direct rays of the sun. A 
trough or tank built as described will be absolutely water-tight, and, 
furthermore, the waterproofing will have cost almost nothing in com- 
parison with the costs of the other materials. 
