CHEMICAL SCIENCE. 273 



of syrup may be detected; but, if it contains less, on adding a drop or two 

 of sulphuric acid to the mixture, a white deposit forms immediately. Gly- 

 cerine dissolved and boiled with water, should not be changed to a darker 

 hue, which would indicate the presence of glucose. Med. Reporter. 



ON THE PREPARATION OF COLLODITJM. BY M. ZINKEISEN. 



To detect the most advantageous process of preparing collodium, the fol- 

 lowing trials have been made by me : 



1. The Codex Medicam. Hamb. prescribes: 



20 parts of dry Nitre, 

 80 parts of English Sulphuric Acid, 

 2 parts of cotton, 



which has been previously treated with soda to be left in contact with the 

 acids only a few minutes. 



Four trials, made according to this formula, yielded, after application of a 

 temperature from 45 to 35 R., from three minutes to one hour and a quar- 

 ter, very little more than 2 ounces of wool each, of which only i could be 

 dissolved in ether, and -^ in alcohol at most; for there remained distinct, 

 undissolved filaments of wool. The quantity of cotton, therefore, appears 

 too large in this process. 



2. According to the prescription of Mann, there are to be taken : 



20 ounces of Nitre, 



31 ounces of English Sulphuric Acid (of 1.830 sp. weight), 

 1 ounce of Cotton, 



which are to be left in contact for a " good while." 



I had the acids working on the wool for one hour and a half, at a tempera- 

 ture of from 45 to 35 R., and, after drying, got 1 ounce and 1 drachm of a 

 very fine, clear, and entirely soluble wool. 



This prescription, however, is too expensive for manufacturing purposes. 



3. Bertram's formula : 



16 ounces of Concent. Sulph. Acid (1.850 sp. w. by mixing 



fuming and English Acids), 

 11 ounces of dry Nitre, and 

 1 ounce of Cotton. 



While mixing the nitre with the acid, the temperature went up as high as 

 GCP R., some brown bubbles of oxygen gas escaping. After cooling tho 

 mixture down to 45 R., the cotton was added, and left in contact for one 

 hour, at nearly the same temperature. After drying, it yielded 1| ounces 

 of wool, which exploded heavily, but was indissoluble. A second trial, at 

 which the cotton was put in at 60 R., yielded no better result. 



In this formula the sulphuric acid is too concentrated and its effects too 

 violent. 



4. Schacht's prescription : 



24 ounces of Sulphuric Acid, 

 16 ounces of Nitre, and 

 1 ounce of Cotton. 



Immediately after mixing the acids, the cotton is to be put in at a temper- 



