758 BLUEING OF METALS BLUE LAWS body is of a bluish color, the lower part of sides and abdomen whitish, a large black spot at the base of pectoral fins ; the jaws are armed with prominent, sharp, and lancinated teeth, the lower with one row, the upper with a second posterior row of small ones; the base of the tongue, vomer, and palatal bones are also crowded with very small teeth; the operculum terminates in two points, not spines, the lateral line beginning just above its posterior angle, and, curving with the body, terminating at the base of the caudal fin ; the fins are covered with scales. It arrives on the coast of the middle states early in the spring, accompanying the weakfish (otolithus regalis, Ouv.) in its migrations, and feeding principally upon it; it is not uncommon in Massachusetts bay in the summer months, where it is often seen chasing the schools of menhaden and mackerel, jump- ing out of water, and so hotly pursuing its prey as to drive large numbers of them upon the beaches. The size varies from 1 to 3 feet in length, the weight from 5 to 14 Ibs., the former being the ordinary weight of those seen in the market. They are among the most swift, strong, and voracious of fishes ; they will bite eagerly at any object drawn rapidly through Bluefish (Temnodon saltator). the water, and advantage is taken of this to oatch them by trolling in sail boats ; so sharp are their teeth that it is necessary to wire the line for a short distance above the hook or spoon. It is so terrible a foe to the mackerel, that the scarcity of the latter fish on the New England coast in 1857 was attributed by the fishermen mainly to its presence. It generally swims near the surface. Toward the latter part of summer it is most excellent eating. It runs up the mouths of rivers even to quite fresh water, being taken in the Hudson as high up as Sing Sing, in the Delaware at Philadelphia, and in the Potomac as far up as Acquia creek. It ranges far along the coasts of North and South America, and, in the opinion of Valen- ciennes, inhabits as a single species both oceans. It is erratic in its habits, and on some coasts does not appear for many years and then sud- denly returns in great numbers. During the last half of the 18th century and the first half of the 19th it disappeared entirely from the coast of New England. BLUEING OF METALS, the process of giving a blue color to metallic substances by heat. Iron when heated becomes first of a light, then of a darker gold color, and finally blue. Steel heated to redness and suddenly cooled is ren- dered hard and brittle. It is restored to any degree of softness by heating it up to certain temperatures and allowing it to cool slowly. These temperatures are precisely indicated by the color of the film of oxide which forms upon its surface. The first perceptible tint is a light straw color, which is produced by the lowest degree, and indicates the hardest temper ; the heat required is from 430 to 460 F. ; it is used for lancets, razors, and surgical instru- ments. At 470 a full yellow is produced ; it is the temper fitted for scalpels, penknives, and fine cutlery. The temperature of 490 gives a brown yellow, which is the temper for shears intended for cutting iron. At 510 the first tinge of purple shows itself; this is the temper employed for penknives. The purple hue which appears at 520 is the tint for table and carving knives. A temperature from 530 to 570 produces various shades of blue, such as are used for watch springs, sword blades, saws, and instruments requiring great elasticity. The different degrees of heat may be exactly regu- lated by plunging the articles in an oil bath, the temperature of which is ascertained by means of thermometers. Blacksmiths usually temper their cold chisels, drills, and other tools, by chilling them from a red heat by im- mersion in water; a bright spot is then filed upon the point, which is then heated in the forge until this spot has assumed the desired color. BLUE LAWS, a term sometimes applied to the early enactments of several of the New Eng- land states, but more frequently limited to the laws of New Haven colony. The origin of the term is not exactly known. The most probable derivation is that given by Professor Kingsley, who thinks the epithet " blue " was applied to any one who in the times of Charles II. looked with disapprobation on the licentiousness of the times. Thus, in Iludibras, For his religion, it was fit To match his learning and his wit ; 'Twos Presbyterian true blue. In the colonies this epithet was applied not only to persons, but to the customs, institutions, and laws of the Puritans. Hence, probably, a belief with some that a distinct system of laws, known as the blue laws, must somewhere have had a local habitation. The existence of such a code of blue laws is fully disproved. The only authority in its favor is Peters, who is no- toriously untrustworthy. The traditions upon this subject, from which Peters framed his stories, undoubtedly arose from the fact that the early settlers of New Haven were uncom- monly strict in their application of the "gene- ral rules of righteousness." Judge Smith, in his continuation of the history of New York, published in "New York Historical Collec- tions," vol. iv., gives evidence against the ex- istence of the blue laws, which is particularly valuable, as it was put on record some 15 years before Peters's history was published. He writes : " Few there are who speak of the blue
