BULLETIN OF THE BUSSEY INSTITUTION. 29 
Pete aS OS a 0.46 * 
RMERHOTIO AGId 3. ve ae 
Reeeomeme Se eo: 120.12 
SUMERENE wh ee 212 —— 
Methods of Analysis. Several handfuls of the spent tan or dye-wood 
were ground to fine powder in a drug-mill, in order to obtain a fair sam- 
ple of the material. Moisture and ash were determined in a special por- 
tion of the powder, by drying and burning in a platinum dish; and nitro- 
gen by means of soda lime, using the very finely powdered woods. Phos- 
phoric acid and potash were determined as follows : 40 grammes of the 
powder were placed in a tall beaker which was covered with an inverted 
funnel. Rather more than enough strong nitric acid to cover the powder 
was poured into the beaker, and the mixture was heated for many hours, 
until, on addition of a fresh portion of the acid, no further decomposition 
of the organic matter could be perceived. The acid liquor was diluted 
with water and filtered, and the residue upon the filter dried, and burnt 
in a platinum dish. Its ashes were dissolved in nitric acid, and the solu- 
tion added to the filtrate, which was then diluted to the volume of half 
a litre. Two 200 cc., portions of the liquid were measured out for 
the analysis. In one of these portions, phosphoric acid was estimated 
by the molybdenum process, after the liquid had been evaporated to dry- 
ness, ignited with carbonate of soda and nitrate of potash, and again 
dissolved. In the other portion, potash was estimated as chloroplatinate 
that Boerhaave and Wiegleb (see his “ Chemische Versuche iiber die alkalischen 
Salze,” Berlin, 1781, pp. 83, 85) have both noticed that lime-water is obtained 
on treating the ashes of spent woods with water. So, too, ashes prepared in 
the Bussey laboratory by burning spent logwood in a muffle, and thereafter cal- 
cining the ashes in a platinum dish to destroy a small trace of carbon that had 
escaped combustion, contained a considerable proportion of quicklime, as has 
been stated in the note on page 28. That the ashes of spent woods are apt to 
contain much carbonate of lime was hinted by John (‘‘ Ernahrung der Pflanzen,” 
p. 56), and proved by De Saussure (‘‘ Recherches,” pp. 293, 297) ; a part of this 
carbonate would naturally suffer decomposition at no very intense heat, and 
since the ashes contain little or no carbonate of potash, the quicklime thus 
formed would readily dissolve as such on the addition of water. 
* The small proportion of potash and phosphoric acid in the ashes of the 
spent dye-wood is a point of considerable practical importance, with regard to 
the use of this substance as fuel. The wet material can, in fact, be burnt very 
advantageously in the Thompson furnace, for heating steam-boilers, since its 
ashes do not attack the grate-bars. But with spent tan, the furnace gives less 
favorable results, and one, if not the sole, reason of this difference is to be found 
in the fact that the ashes of the spent tan, which still contain considerable quan- 
tities of potash and phosphoric acid corrode the grate-bars of the furnace. These 
bars, though made of the most refractory fire-clay, are exposed to intense heat, 
and are consequently peculiarly liable to suffer from the action of an alkaline 
flux. 
