Page:The American Cyclopædia (1879) Volume III.djvu/67

 BONE BONE ASH 61 of the interior the strength of the compact ex- terior is increased without the disadvantage of an increase of weight. The reparative power of bone is of the greatest importance in surgery. When a bone is broken, blood is effused, with the coagulum of which a semitransparent lymph is subsequently mingled, covering the surfaces of the wounded parts ; in the course of two to three weeks this is gradually condensed by an interstitial change, which converts it into a substance resembling temporary cartilage ; ossi- fication takes place in this in a nearly uniform manner, and the whole is transformed in from four to six weeks into a spongy osseous mass which holds the ends of the bone together ; this provisional callus, as Dupuytren called it, is gradually absorbed during the succeeding months, while the permanent callus is being deposited between the contiguous surfaces of the compact tissue ; the permanent callus has all the characters of new bone. When this reparative process is interfered with by med- dlesome surgery or constitutional disease, the union takes place merely by ligament, con- stituting sometimes a false joint. In reptiles and fishes the cancellated structure usually ex- tends throughout the shaft, which is not so well divided into solid bone and medullary cavity as it is in mammalia. Lacunaa are highly char- acteristic of true osseous structure, being never deficient in the minutest parts of the bones of the higher vertebrata, though those of fishes are occasionally destitute of them. The lacu- nae of birds are longer and narrower than those of mammals, and the canaliculi are remarkably tortuous ; in reptiles they are remarkably long and narrow, and in fishes very angular, with few radiations ; their size is not in relation to that of the animal, since there is no percepti- ble difference between their size in the large extinct iguanodon and in the smallest living lizard. From the emarginated and festooned outline often seen on sections of bone, Dr. Car- penter, in his "Principles of Human Physiol- ogy," expresses the opinion that the older por- tions of the osseous substance are removed from time to time, and that the irregular out- line thus presented by the Haversian spaces is caused by the partial or complete removal of the Haversian system ; in their stead newly formed tissue is deposited ; this alternate absorption and reproduction takes place at all times of life, though its energy diminishes with the in- creasing age of the individual. The complete development of the osseous system characterizes the final stage of the growth of the organism ; the vertebral column does not completely ossi- fy in its spinous and transverse processes until the 25th or 30th year ; the ossification of the head and the tubercle of the ribs, commencing soon after puberty, is not continued to the body of the bone till some years after ; the ossi- fication of some of the cartilages of the sternum is often not completed even in quite advanced age ; the bones of the skull are united within a few years after birth. As long ago as Aris- totle's time, the duration of the life of animals was measured by their period of growth. Buf- foh had the same idea, for he says : " The dura- tion of life, to some extent, may be measured by the time of growth." Animals and man grow only until union takes place between the shafts and the ends of the bones ; this union occurs in man at the age of 20 years, in the camel at 8, in the horse at 5, in the ox and lion at 4, in the dog at 2, in the cat at 1, and in the rabbit at 1 year. Recent observa- tions go to show that animals live about five times their period of growth ; this would give, according to Flourens, as the age at which man should arrive, if he lived in accordance with the laws of physiology and hygiene, about 100 years; for the camel 40, the horse 25, the ox and the lion 20, the dog 10, the cat about 8, the rabbit 5 years. In an elephant which died at the age of 30 years, the ends of the bones were not united to the shafts, so that it may be confidently asserted that this animal lives more than 150 years. BONE, Henry, an English enamel painter, born at Truro, in Cornwall, Feb. 6, 1755, died in London in December, 1834. He was brought up to the art of painting on china, and was afterward employed in London in enamel painting on watches, lockets, and other jewelry. His remarkable skill in this work attracted special attention about the year 1800. From that time he devoted him- self to painting portraits or copying celebrated pictures on ivory or in enamel. He used larger plates than had been employed for a similar purpose before; his copy of Titian's "Bacchus and Ariadne," which was sold for 2,200 guineas, is 18 inches by 16. Among his other celebrated pictures are " Hope Nursing Love," after Sir Joshua Reynolds, the " Death of Dido," and several collections of historical portraits. A series of 85 portraits of illustri- ous characters in the reign of Elizabeth occu- pied his leisure for 25 years, and was finished after his death by his son H. P. Bone. He be- came a member of the royal academy in 1811. BONE ASH. Bones, when calcined in open fire, lose all their organic matters and part of the carbonic acid gas they contain, by which their weight is diminished about two thirds. The residue is a dry, friable, and white mass, of the original form of the bones. Pulverized, the powder is grayish white. It consists of basic phosphate of lime, with some lime, fluor- ide of calcium, carbonate and sulphate of soda, and phosphate of magnesia. The sulphur of the sulphate comes from the cartilage. Pre- pared from the bones of cattle, the proportion of phosphate of lime is about 90 per cent.; from human bones, about 86 per cent. Other matters may be removed by dissolving in hy- drochloric acid, and precipitating by ammonia, when the phosphate of lime and a very small quantity of phosphate of magnesia alone are left in the solution. Bono ash, ground to pow- der, is made into a paste with gum water, or