274 ANNUAL OF SCIENTIFIC DISCOVERY. 



ature of 45 R., and left in contact therewith for one hour, during which 

 time the mixture cooled down to 35 R. 



Result : 1 ounce and 3 drachms, easily and completely soluble, burning 

 very slowly. This collodium answers every expectation. 



5. Prescription of Brctschneider and Liidersen : 



6 ounces of fuming Sulph. Acid (1.850), 

 6 ounces of fuming Nitric Acid (1.410), 

 ounce of Cotton 



the cotton to be put in in halves, forty-five minutes in contact, at from 40 

 to 25 R. 



Result : 5 drachms, yellowish, quickly exploding, swelling to a gelatinous 

 mass, with 16 parts of ether and 1 part of alcohol, and yielding, even with 32 

 parts of ether, a very thick collodium, the coat of which was very thin and 

 transient. 



A second trial, at which the cotton had been left in the mixture only for 

 10 minutes, yielded the same result. 



6. Konig's formula : 



8 ounces of fuming Sulph. Acid (1.840), 

 4 ounces of fuming Nitric Acid (1.410), 

 ounce of Cotton, dipped in successively. 



At the first trial five minutes' influence, at 45 R. ; at the second trial, one 

 hour's influence, at 50 to 35 R. The first trial yielded an entirely insoluble 

 wool ; the second, a wool only partially soluble both of them, however, 

 very explosive. 



The prescription of Schacht is, undoubtedly, the most advantageous, espe- 

 cially in a pecuniary point. In eight trials, with l ounce of cotton each, I 

 got 17] ounces of wool, and 20 pounds of very fine collodium. I have fur- 

 ther to state, that I made these trials with three different kinds of cotton. 

 The chief points to be observed, in order to come to a satisfactory result, 

 are, undoubtedly, the weight of the sulphuric acid, the temperature of the 

 mixture, and the duration of the process. According to my experience, the 

 sulphuric acid should not weigh below 1.820, and not above 1.840; the most 

 advantageous temperature is 45 to 35 R., which, in general, generates of 

 itself, when the dry and completely cooled nitre is mixed with the acid. The 

 time of contact should not be less than half an hour, in order that all the 

 filaments of the cotton be penetrated. A good prepared collodium wool 

 will, however, not be decomposed if left under the influence of the acids even 

 for a longer time. 



It is very advantageous not to dry the wool by heat, but by repeated pres- 

 sure between blotting-paper. Druggist's Circular. 



GERMAN YEAST. 



Mr. Henncl, of England, has patented the manufacture of German yeast 

 from flour. To obtain 10 pounds of this German yeast, the inventor takes 

 2? pounds of flour of malted wheat, the same of flour of malted barley, and 

 the same of rye flour. To this mixture water is added (at 30 Reaumur), 

 and the mass stirred to a thin paste. This paste is then raised to 45 R. 

 by hot water, and afterwards cooled down to 30 R. ; next are added 2 

 pounds of wheat starch dissolved in Cold water ; and 5 ounces of double 



