42 THE FARMER AT HOME. 



a mann jr, that the operator has time to run out of the reach of the 

 fragments of the rock. 



This process, which is both tedious and dangerous, is now abandon- 

 ed for one which is more simple and effectual, and which consists 

 merely in introducing a straw, filled with gunpowder, among the 

 powder at the bottom of the cylindrical hole in the rock, and filling 

 the rest of the cylindrical hole witL loose sand. By applying a match 

 to the gunpowder in the straw, an explosion takes place ; and, instead 

 of the loose sand being driven out of the cylindrical hole, as might 

 naturally be expected, the rock is completely shivered in pieces. Mr. 

 Jessop tried the experiment with great success on some of the hard 

 rocks at Fort William, acd also on the lime works at Bristol. 



BLINDNESS. No animal is so subject to blindness as the 

 horse, and in most cases it can clearly be traced to the treatment they 

 receive. Severe drawing in the harness, or racing, either on the 

 course or otherwise, will not urifrequently produce blindness, some- 

 times temporary, but often permanent. An examination of the pupils 

 of the eye, will most usually enable an observer to determine whether 

 there is blindness or not. If the pupils, when exposed to light after 

 being in a dark stable, contract, the horse is not blind ; if they con- 

 tract unequally, or one not at all, then the vision is imperfect, or gone 

 in one of the eyes. The hand placed close over the eye for a few 

 minutes, so as to render the eye dark, will show the dilation or con- 

 traction of the pupil, when no other convenient means of excluding 

 light are at hand. A horse, blind with both eyes, will usually have 

 his ears in constant motion, directing them in quick succession to 

 every quarter, relying on hearing rather than sight ; and, he will lift 

 his feet high, as if he were stepping over some obstacle, when there 

 is actually nothing in the way. 



BLOOD. The circulating fluid of animal bodies, and by means 

 of which the functions of nutrition and life are carried on. Blood is 

 usually divided into arterial blood, which is that given by the lungs 

 to the heart, and by that thrown into the arteries of the system, and 

 the venous blood, which is returned to the lungs through the veins 

 from the surface and extremities. The venous blood is of a dark 

 purple hue when passed into the lungs, and it leaves them of a rich 

 vermilion color. This change is effected by the absorption, while in 

 the lungs, of oxygen, from the atmospheric air with which they are 

 filled in breathing. 



Blood is of much use in some of the manufacturing processes, some 

 valuable coloring pigments being derived from it. From the large 

 quantities of albumen it contains, it is the principal ingredient in free- 

 ing sugar or molass2s from its impurities, previous to the conversion 

 into lump and loaf sugar. Blood is found to be one of the most 

 powerful manures when applied to the ground, and large quantities 

 of it, mixed with other materials, are oV-tained from the slaughter- 



