Oftentimes it is necessary to use an alloy which will expand on cooling. Such an alloy is obtained by melting together 9 lbs. of lead, 2 lbs. of antimony, and 1 lb. of bismuth. The alloy is used to fasten bolts firmly into foundation stones. The process is as follows: After the bolt hole is drilled in the stone a couple of short, small holes are drilled at an angle to the big hole. As the metal is poured in, it flows around the bolt and also into these small holes. On cooling, the metal expands and for this reason it is almost impossible for the bolt to pull out. When drilling holes in stone, water is always used and care must be taken to see that the holes are dried out by the use of red-hot iron rods before the melted metal is poured in. If this precaution is not taken, the metal will blow out, and may burn the hands and face of the man who is pouring it in.