LE – MU

LEATHER VARNISH.— See Varnish. LEATHER WATERPROOFING.— See Waterproofing. LEMONS.— See also Essences, Extracts, and Fruits. Preservation of Fresh Lemon Juice.—The fresh juice is cleared by gently heating it with a little egg albumen, without stirring the mixture. This causes all solid matter to sink with the coagulated white, or to make its way to the surface. The juice is then filtered through a woolen cloth and put into bottles, filled as full as possible, and closed with a cork stopper, in such a way that the cork may be directly in contact with the liquid. Seal at once and keep in a cool place. The bottles should be asepticized with boiling water just before using. LEMON EXTRACT (ADULTERATED), TESTS FOR.— See Foods. LEMON SHERBET POWDER.— See Salts, Effervescent. LEMONADES, LEMONADE POWDERS, AND LEMONADE DROPS.— See Beverages. LEMONADE POWDER.— See Salts, Effervescent. LENSES AND THEIR CARE.— Unclean Lenses (see also Cleaning Preparations and Methods).—If in either objective or eyepiece the lenses are not clean, the definition may be seriously impaired or destroyed. Uncleanliness may be due to finger marks upon the front lens of the objective, or upon the eyepiece lenses; dust which in time may settle upon the rear lens of the objective or on the eye lens; a film which forms upon one or the other lens, due occasionally to the fact that glass is hygroscopic, but generally to the exhalation from the interior finish of the mountings, and, in immersion objectives, because the front lens is not properly cleaned; or oil that has leaked on to its rear surface, or air bubbles that have formed in the oil between the cover glass and front lens. Remedy.—Keep all lenses scrupulously clean. For cleaning, use well-washed linen (an old handkerchief) or Japanese lens paper. Eyepieces.—To find impurities, revolve the eyepieces during the observation; breathe upon the lenses, and wipe gently with a circular motion and blow off any particles which may adhere. Dry Objectives.—Clean the front lens as described. To examine the rear and interior lenses use a 2-inch magnifier, looking through the rear. Remove the dust from the rear lens with a camel's-hair brush. Oil Immersion Objectives.—Invariably clean the front lens after use with moistened linen or paper, and wipe dry. In applying oil examine the front of the objective with a magnifier, and if there are any air bubbles, remove them with a pointed quill, or remove the oil entirely and apply a fresh quantity. LETTERS, TO REMOVE FROM CHINA.— See Cleaning Preparations and Methods, under Miscellaneous Methods. LETTER-HEAD SENSITIZERS.— See Photography, under Paper-Sensitizing Processes. CEMENTS FOR ATTACHING LETTERS ON GLASS.— See Adhesives, under Sign-Letter Cements. Gold Lettering.— This is usually done by first drawing the lettering, then covering with an adhesive mixture, such as size, and finally applying gold bronze powder or real gold leaf. A good method for amateurs to follow in marking letters on glass is to apply first a coat of whiting, mixed simply with water, and then to mark out the letters on this surface, using a pointed stick or the like. After this has been done the letters may easily be painted or gilded on the reverse side of the glass. When done, wash off the whiting from the other side, and the work is complete. Bronze Lettering.— The following is the best method for card work: Write with asphaltum thinned with turpentine until it flows easily, and, when nearly dry, dust bronze powder over the letters. When the letters are perfectly dry tap the card to take off the extra bronze, and it will leave the letters clean and sharp. The letters should be made with a camel's-hair brush and not with the automatic pen, as oil paints do not work satisfactorily with these pens. For bronzed letters made with the pen, use black letterine or any water color.