Excerpt from The American Journal of Pharmacy, 1878, Vol. 50
In evaporating percolates, I find it almost impossible to work large amounts with any degree of satisfaction. A skim usually forms over the surface, which frequently almost completely prevents evaporation from beneath; from eight to ten days it may be expected will be required when this is the case, and even then all the liquid may not be driven off. The addition of a known amount of dry sand facilitates the Operation; but I seldom use this plan, as frequently the residuum is to be examined, and the sand interferes. I favor moderately small portions of liquid, and in the experiments recorded here the second part of the first is the only example where more than one cubic centi meter was evaporated. Great care must be taken to expel all the alco hol from residuums, but too great a heat must be guarded against with an equal degree of caution. All extractive matters are not like that obtained from cimicifuga. A heat of 150° to 160° Fah. Is sufficient for this article. I obtain the requisite temperature from a steam-coil drying-room; cold air passes over the coil of pipes at the bottom of the room, and, circulating around alternate ends and over the shelves, escapes at the top.
I take three equal amounts of each percolate; if there is sufficient variation to justify, I average the weight of the residuums. Mistakes may be very easily made, and often it is a satisfaction to have dupli cates, especially where the result is contrary to preformed opinions.
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