EquivalentsWe can no more make progress in chemistry without studying its principles and its laws, than an artist can paint a perfect picture without knowing the rules of perspective ; it is for this reason that we have recently turned from the subject of experiments to that of doctrines, especially as we hope that some of our readers will at a future day give us credit for being the fingerpost on their road of life which pointed to the path leading to honor The term "equivalent " in chemistry has much the same meaning as it has in ordinary things An equivalent means of the same value ; thus, twenty shillings in silver (English currency) are equivalent to one sovereign in gold In the laboratory, the word equivalent implies an atom of matter that is equal to another of a different kind ; thus, aswe learned in a previous article, that every atom of an element has a specific weight compared with another atom, this weight has, by the consent of philosophers, been denominated its " equivalent" Hence, 28 parts of iron, combining with sulphur, always unite with 16 parts of that fiery element ; let the weight of the materials be in grains, ounces, or pounds, the same proportion is always there in sulphuret of iron You will say, for the sake of argument, "But suppose we only put 14 parts of iron to 10 parts of sulphur, they will unite" Chemical doctrine says "No," for there will be free sulphur containing no iron; in the mixture, the 14 parts of iron will have combined with 8 of sulphur, which is in the same proportion stated, for as 28 : 16 : : 14 : 8 It is thus we call 28 the "equivalent" of iron, and 16 the " equivalent" of sulphur, because we have made hydrogen as the standard of comparison, and have fixed upon 1 as its equivalent, and the base or unit of calculation in measuring the equivalents of all other bodies A list of equivalents or atoms in weight is given in every elementary work on chemistry ; it is, therefore, sufficient for us to point out the road where the philosopher's stone may be found