326 
Wool in Relation to Science with Practice. 
been satisfactorily explored. Let us, under the microscope, com- 
pare and fix the images of various wools of known properties, 
and so "mark, learn, and inwardly digest" the characteristic 
and essential differences of structure, upon which depend their 
respective economic values. 
Chemistry. — Dr.Voelcker, whose kindness is proportioned to his 
abounding stores of available knowledge, has favoured me with the 
following interesting communication on the chemistry of wool : — 
» "39, Argyll Eoad, Kensington, W. 
" February 5th, 1875. 
" My Loed, — The most recent investigations on the chemical constitution 
of wool I find were made a year or two ago in Germany by M. Miirker and 
E. Schulz. 
" Eaw sheep's wool contains : — 
1. Hygroscopic water (moisture). 
2. Fatty matters. 
3. Yolk of wool (fatty acids combined with potash, and soluble in 
water and partly also in alcohol). 
4. Pure wool-fibre. 
5. Dirt. - 
"The relative proportions of these constituents vary greatly in different 
species of wool. 
"According to Marker and E. Schulz's analyses, raw wool yields from 42 to 
50 per cent, pure wool-fibre (dried at 212° Fahr.), 10 to 18 per cent, of 
moisture, 7 to 10 per cent, of fatty matter, 20 to 22 per cent, of yolk (soluble 
in water), and variable proportions of dirt. 
"The jjortion soluble in water (yolk) amounting to 20 to 22 per cent, 
contains fatty acids — oleic and similar fatty acids — combined chiefly with 
potash and a small proportion of nitrogenous organic matter. The watery 
solution, or the washings of wool with water evaporated to dryness, yields an 
extract which consists of : — 
Organic matter, chiefly fatty compounds, con-) cq.qq 
taining nitrogen (1-82) ^ 0» J- 
Mineral matter (ash) / .. 41*08 
100-00 
*' The mineral portion (ash) of this extract yields from 59 to 84 per cent, of 
potash. 
" In some places the ];;otash is recovered technically from ^hese wool- 
washings. 
"In an air-dry state raw wool contains about 8a per cent, of mineral matter 
(ash), which is removed by washing. Washed wool (wool deprived of the 
yolk by washing in water) seldom contains more than 1 per cent, of mineral 
matter (ash). 
" Pure wool (fibre) dried at 212° Fahr, consists of: — 
Carbon 49-25 
Hydrogen 7-57 
Nitrogen 15-86 
Sulphur 3-66 
Oxygen 23 -06 
100-00 
" It will be soon that wool not only is rich in nitrogen, hut also contains a 
