A Theory as to the Origin of Petroleum.—­Professor Mendelejef has recently advanced the theory that petroleum is of purely mineral origin and that the formation of it is going on every day.  He has, moreover, succeeded in producing artificial petroleum by a reaction that he describes, and he states that it is impossible to detect any difference between the natural product and the manufactured article.  His theory is as follows:  [Transcriber’s Note:  The original text reads ‘Infilration’] Infiltration of water, reaching a certain depth, come into contact with incandescent masses of carburets of metals, chiefly of iron, and are at once decomposed into oxygen and hydrogen.  The oxygen unites with the iron, while the hydrogen seizes on the carbon and rises to an upper level, where the vapors are condensed in part into mineral oil, and the rest remains in a state of natural gas.  The petroleum strata are generally met with in the vicinity of mountains, and it may be granted that geological upheavals have dislocated the ground in such a way as to permit of the [Transcriber’s Note:  The original text reads ‘admistoin’] admission of water to great depths.  If the center of the earth contains great masses of metallic carburets, we may, in case this theory is verified, count upon an almost inexhaustible source of fuel for the day when our coal deposits shall fail us.

How Vaseline is Purified.—­The residuum from which vaseline is made is placed in settling tanks heated by steam, in order to keep their contents in a liquid state.  After the complete separation of the fine coke it is withdrawn from these tanks and passed through the bone black cylinders, during which process the color is nearly all removed, as well as its empyreumatic odor.

The Latest and Best Process Employed by Cutters and Others in Etching Names and Designs on Steel.—­Take copper sulphate, sulphate of alum and sodium chloride, of each 2 drachms, and strong acetic acid 1-1/2 ounces, mixed together.  Smear the metal with yellow soap and write with a quill pen without a split.

The History of the Discovery of Circulation of the Blood recapitulated, divides itself naturally into a series of epoch-making periods:  1.  The structure and functions of the valves of the heart, Erasistratus, B.C. 304. 2.  The arteries carry blood during life, not air, Galen, A.D. 165. 3.  The pulmonary circulation, Servetus, 1553. 4.  The systemic circulation, Caesalpinus, 1593. 5.  The pulmonic and systemic circulations, Harvey, 1628. 6.  The capillaries, Malpighi, 1661.

How to Make Hand Fire Grenades.—­Make your hand grenades.  Fill ordinary quart wine bottles with a saturated solution of common salt, and place them where they will do the most good in case of need.  They will be found nearly as serviceable as the expensive hand grenades you buy.  Should a fire break out, throw them with force sufficient to break them into the center of the fire.  The salt will form a coating on whatever object the water touches, and make it nearly incombustible, and it will prove effectual in many cases, where a fire is just starting, when the delay in procuring water might be fatal.