130 TRICIIOLOG1A MAM.MALHM: 



Ure gives the specific gravities of cotton, 1.47 to 1.50; of linen, 1.50; of silk, 1.30; 

 mummy cloth, 1.50; wool, 1.26. The Doctor found some difficulty in taking the specific 

 gravity of wool, owing to its greasy nature, which prevented it from sinking in water.* 



Our phial, for taking the specific gravities, when empty weighs 373 grains; when filled 

 with distilled water, at 60 F., up to two marks made upon its neck, (one to note the upper, 

 and the other to note the lower surface of the concavity formed by capillary attraction,) 

 it holds 1,000 grains. We have a thermometer tube (with no mounting) small enough to 

 enter the phial. Upon this tube is marked, with a diamond, the single point of 60 F.; 

 when we are about to perform the experiment upon wool, we weigh the quantity required, 

 and boil it m a weak solution of soda, to extract the grease of the exterior. After having 

 dried it again, and re-weighed it, (in order to ascertain the loss sustained,) we proceed in 

 the way directed by Dr. Ure. 



Dr. John Davy (in Researches Phys. and Anat, p. 138. 1840,) gives the following 

 specific gravities of hair : 1.280, 1,393, 1,278, 1,290, 1,275, 1,345, 1,328, and 1,300. 



OF THE INCINERATION OF PILE. In Graham's Elem. of Chem., 702, it is stated that 

 hair of the beard left 0.72 per cent, of ashes. Blonde colored hair of the head, 0.3 per 

 cent.; black hair of a Mexican, 2 per cent. 



Achard found from the combustion of one pound of hair, the following cinders, viz : 

 Hair of the head of Man, - I drachm 20 grains. 

 Pile of a Goat, - 1 30^ " 



" Hog, 1 55 



" " Calf, - - 2 40 



* "To ascertain with precision the specific gravity of textile fibres (he says) is a more troublesome experiment than would 

 at first sight appear, and the point has, for this reason probably, been left hitherto undetermined. Having bestowed some 

 pains upon the subject, and having contrived a simple method susceptible of giving exact results, I shall here state it in 

 detail. I take a taper-necked phial, capable of holding nearly 2,000 grains of distilled water poise it when so filled, mark 

 the line of the neck where the water stands, and then pour out exactly 200 grains of the water. I next weigh out SOU grains 

 of the textile substance, lay them on a clean tray, and proceed slowly to introduce them into the phial, in small quantities at 

 a time, pressing each portion down with a wire, so as thoroughly to wet it and to extrude every particle of the entangled air. 

 Whenever so much fibrous matter has been introduced as to raise the water-line to its primitive mark in the neck, there bus 

 obviously been added a volume of the matter equal to that of 200 grains of water; and the additional weight communicated 

 to the phial being divided by two, will therefore be the quotient, expressing the specific gravity of the substance compared 

 to the water reckoned, 100. From the spongy nature of cotton, wool, flax and silk, much water is absorbed into their pores, 

 and this is provided for in the 1,800 grains, or thereabouts, which are purposely left in the phial at the beginning of the 

 experiment. If the raw filaments of cotton, wool, flax or silk, are made the subject of this experiment, they are apt to retain 

 so many minute particles of air as to cause fallacious results. Thus, after the labor of several hours in filling the vacant 

 space of the phial with woollen fibres, and in churning them, so to speak, under water, to expel the air adhering to them, I 

 have found it impossible to introduce 200 grains of wool ; and I might thence have concluded, that 206 grains of wool occupy 

 a greater space than IIUO grains of water. But if we take shreds of flannel, freed from grease by washing, which are readily 

 moit-tened, we then find that 52 grains of it may bo introduced into the space (if 200 grains of water; and we are entitled 

 to affirm, that the true specific gravity of wool is 1.26 compared to water 100 or 1,260 by the ordinary notation. By a 

 similar procedure, I have found the specific gravity of cotton to be from 1.47 to 1.50 ; of linen, 1.50; of silk, 1.30 ; of mummy 

 cloth, 1.50. It was stated that a definite weight (300 grains) of each substance was weighed out at the commencement of 

 each experiment a precaution taken for the purpose of verifying the result since that weight, minus the weight of the 

 residuary portion, ought to be equal to the increase of weight in ihe phial. If these two quantities ditto red, the experiment 

 was considered to be inexact, and to require repetition." (Philos. of Manuf., p. 97.) 



