p. W. PHILIPPI ON POTATO-STARCn AND GRAPE-SUGAR. 391 



filters ; then a wooden filter, of cylindrical form, which is lined 

 on the inside with copper sheets, or a copper filter. This filter 

 has two copper bottoms, of which one is sieve-like, and fastened 

 to the sides. When this filter is used, a moistened cotton cloth 

 must be spread on the bottom ; after which, a layer of bone-black, 

 about ten inches high, is brought on the same; it is then care- 

 fully moistened with pure water, and stamped gently. In this 

 manner it will be continued with the bone-black until three 

 fourths of the filter is filled. The false bottom is placed firmly 

 on this filling, and covered with a cotton cloth moistened. 



The neutral solution of sugar is brought in the linen filter first, 

 from which the results will be put in the last-mentioned. The 

 sediment remaining in the linen filters may be taken out, mixed 

 with a little water, and then put under the press. The cake re- 

 maining in the press (gypsum and bone-black) will make an ex- 

 cellent manure. The solution of sugar received from this filter 

 has lost the improper ingredients contained in it, as gypsum, etc., 

 and is ready for steaming. 



4. The first boiling of the Sugar. — The apparatus for this purpose 

 vary as much in construction as in efficiency. So much is certain, 

 that for this work it is not necessary to use a vacuum apparatus. 



5. Second Filtration through Bone-hlaclc. — This sirup will re- 

 quire some pressure to pass through the filter, and apparatus for 

 this purpose has been devised. The work of Dr. Philippi con- 

 tains drawings of the apparatus used in this manufacture, which, 

 however, we do not think it necessary to reproduce. 



6. The last Steaming^ and the concentration of the Grape-sugar. — 

 For this purpose a rotary apparatus is preferable. When the sirup 

 is concentrated to a consistence of 42° B,, it is drawn off" into a 

 cooling- vat, and well stirred for half an hour. The forms to re- 

 ceive the sugar now must be invariably of wood, and must be 

 moistened with cold water before the sugar is put into them. 

 When the sugar has sufficiently hardened not to receive impres- 

 sions from the pressure of a finger, it may be loosened in the forms. 

 It is now brought into a room heated from 16° to 18° E., and kept 

 to dry from 5 to 10 hours, after which the sugar will be ready 

 for market. The analysis of Professor Dr. Fresenius, in Wies- 

 baden, showed it to consist of 



Diy sugar 87.47 



Water 12.28 



Gypsum 0.25 



The analysis proved farther that the grape-sugar was of an ex- 

 cellent light color, and of sweet, pure taste. Dissolved in water, 

 it formed a very clear and pale sirup, and was free from dextrine, 

 copper, or other metals. 



