DARTARS. 



DECIDUOUS. 



States, see Dr. Darlington's Flora Cestrica, un- 

 der the head of Bromus secalinus, Eye bromus, 

 Cheat or Chess. 



DARTARS. In farriery, a sort of scab of 

 ulceration taking place on the chin, to which 

 lambs are subject. 



DAUBING. A word meaning provincially 

 plastering with clay. 



DAUBY. A word applied to land when wet, 

 signifying clammy or sticky. 



DAVYING. A provincial word applied to 

 the getting of marl out of the face of the cliffs 

 on the sea-coasts, when it is drawn up by a 

 wince. 



DEADLY NIGHTSHADE. See BELLA- 

 DONNA and NIGHTSHADE. 



DEAD-NETTLE (Xarmum). A genus of 

 perennial or annual European herbs, of which 

 twenty species are described. Among which, 

 are the white dead-nettle (L. album) and red 

 dead-nettle (L. piirpurcum) to which medicinal 

 properties are ascribed. The herbage of the 

 former is scarcely eaten by cattle, and has a 

 slightly fetid scent. The flowers abound with 

 honey. Low says (Frac. Agr. p. 446) it is 

 sometimes common in corn-fields, and having 

 a strong, creeping, perennial root, it should be 

 carefully extirpated. 



DEAD-TOPS. A disease incident to young 

 trees, which may be cured by cutting off the 

 withered parts close to the nearest sound twig 

 or shoot, and claying them over, in the same 

 manner as practised in grafting. 



DEAF. A provincial word signifying blast- 

 ed or barren, as a deaf ear of grain, a deaf-nut, 

 &c. or such as have no grain or kernel. In 

 such cases it is probable that the pollen has 

 been scattered, and never communicated the 

 fertilizing principle to the seed, which resem- 

 bles in this respect an addle egg. 



DEAL (Sax. oeian, to divide; Ger. dielen; 

 Dutch, declen; Dan. rfaefcr). The small thick- 

 ness into which a piece of timber of any sort 

 is cut up ; but in England the term is now im- 

 properly restricted in its signification to the 

 wood of the fir tree, cut up into thicknesses in 

 the countries whence deals are imported. 



DEATH-WATCH (Anobium tesstllatum ; 

 Tenties pulsatoriitm, Lin.)- The popular name 

 in England for a small insect that harbours 

 chiefly in old wood. It is produced from a 

 very minute white egg, hatched in March; in 

 the perfect state these insects are about y s ff ths 

 of an inch in length, and of a dark brown, spot- 

 ted colour. They make a ticking noise, 

 which is an expression of mutual affection 

 between the male and female, but which has 

 and is still superstitiously imagined by some 

 to be an omen of death. See Penny Cyclo. 

 vol. viii. 



DEBRIS (Yr.debre'e). In geology, any worn 

 materials, such as fragments of rocks, ruins, or 

 rubbish. 



DECAY. All vegetable as well as animal 

 substances undergo two processes of decompo- 

 sition after death. One of these is named 

 fermentation, the other decay, putrefaction, or 

 eremacausis. The decay of woody fibre (the 

 principal constituent of all plants) is accom- 

 panied by a phenomenon of a peculiar kind. 

 This substance, in contact with air or oxygen 

 51 



gas, converts the latter into an equal volume 

 of carbonic acid, and its decay ceases upon 

 the disappearance of the oxygen. If the car- 

 bonic acid is removed, and oxygen replaced, 

 its decay recommences, that is, it again con- 

 verts oxygen into carbonic acid. Woody fibre 

 consists of. carbon and the elements of water; 

 and if we judge only from the products formed 

 during its decomposition, and from those form- 

 ed by pure charcoal, burned at a high tempe- 

 rature, we might conclude that the causes were 

 the same in both : the decay of woody fibre 

 proceeds, therefore, as if no hydrogen or 

 oxygen entered into its composition. 



A very long time is required for the comple- 

 tion of this process of combustion, and the 

 presence of water is necessary for its main- 

 tenance : alkalies promote it, but acids retard 

 it ; all antiseptic substances, such as sulphur- 

 ous acid, the mercurial salts, empyreumatic 

 oils, &c., cause its complete cessation. 



Woody fibre, in a state of decay, is the sub- 

 stance called Jutnnia. 



The property of woody fibre to convert sur- 

 rounding oxygen gas into carbonic acid di- 

 minishes in proportion as its decay advances, 

 and at last a certain quantity of a brown coaly- 

 looking substance remains, in which, this pro- 

 perty is entirely wanting. This substance is 

 called mould ; it is the product of the complete 

 decay of woody fibre. Mould constitutes the 

 principal part of all the strata of brown coal 

 and peat. 



Eremacausis (from gm* *low, and x*ti?, 

 combustion) is the act of gradual combination 

 of the combustible elements of a body with the 

 oxygen of the air ; a slow combustion or oxida- 

 tion. 



The conversion of wood into humus, the 

 formation of acetic acid out of alcohol, nitri- 

 fication, and numerous other processes, are of 

 this nature. Vegetable juices of every kind, 

 parts of animal and vegetable substances, 

 moist sawdust, blood, &c., cannot be exposed 

 to the air, without suffering immediately a pro- 

 gressive change of colour and properties, 

 during which oxygen is absorbed. These 

 changes do not take place when water is 

 excluded, or when the substances are exposed 

 to the temperature of 32, and different bodies 

 require different degrees of heat, in order to 

 effect the absorption of oxygen, and, conse- 

 quently, their eremacausis. The property of 

 suffering this change is possessed in the high- 

 est degree by substances which contain ni- 

 trogen. (Liebig, Org. Chem. Part 2d.) 



In the Appendix to the Third Report of the 

 Agriculture of Massachusetts, 1840, Dr. S. L. 

 Dana adduces the following example, to show 

 that even with the presence of moisture, vege- 

 table matter will not decay, if air is excluded. 

 A piece of a white birch tree was taken from 

 a depth of twenty-five feet below the surface, 

 in Lowell. "It must have been inhumed there 

 probably before the creation of man, yet this 

 most perishable of all wood is nearly as sound 

 as if cut from the forest last fall." See NI- 

 TRIFICATION. 



DECIDUOUS (Lat. decido, I fall off). In 

 zoology, a term applied to parts which have 

 but a temporary existence, and are shed during 

 2 i. 2 401 



