PYBOXYLINE. This substance, which when dissolved in ether forms collodion, is made by acting on lignin with a diluted mixture of sulphuric and nitric acids represented by the formula HO, HO, HO, the temperature being uniformly maintained at from to according to the quality of the collodion required.
It may either be made from cotton wool, or linen rags. The rags must first be boiled in a strong solution of soda, and then thoroughly washed. The mode of proceeding will he understood from the following description, extracted from a treatise by the author on the " Positive Collodion Process." "Procure some dry cotton wool chemically clean, some pure sulphuric acid, S. G. 1.84, some pure nitric acid, S. G. 1.5, and some rectified sulphuric ether, S. G. •750.
" Use the fire-place of an outbuilding for the experiments. Put an old frying pan filled with sand upon the fire, and in this sand bath place a pie-dish containing water heated to about 170° Faht. Then procure a breakfast cup and a couple of long thick glass rods.
" 1st Experiment.—Put into the cup 5 drachms Nitric Acid, by measure.
5 drachms Sulphuric Acid „ 25 grains Cotton Wool.
"Dense suffocating fumes rise from the mixture ; these should escape up the chimney. Keep working the cotton wool about with the glass rods for 5 minutes, during which time the temperature of the mixture should be 150°. The temperature of the water in which the cup stands being about 170°, that of the mixture in the cup will be as nearly as possible 150°; but you must test it with a thermometer, the ball of which can be inserted in the mixture ; for the preservation of an even temperature is of the utmost importance.
" At the end of five minutes, remove the cup, throw away the mixed acids, and put the cotton into a pail of water. Wash it quickly, opening it well, and rousing it about in the water. Then continue the washing in a basin, changing the water several times, and squeezing the cotton after each washing between your hands.
" When you have thoroughly washed and squeezed out all traces of the acids in this way, pull the cotton out into a large loose ball, and hang it up to dry gradually in a clean piece of netting. The cotton when dry looks pretty much as it did at first, but you feel a peculiar harshness about it.
" The first experiment yields pyroxylin of the most explosive kind. Be careful therefore of accidents.
" Repeat the experiment ten or twelve times, adding in the second experiment 30 minims of water to the acids, and increasing the quantity of water added by 30 minims in each fresh experiment. The twelfth experiment will therefore contain, in addition to the acids, 330 minims, d. e. 5i drachms of water.
" We will now suppose the various samples of gun-cotton to be dry, and ready for an investigation of their properties.
" Pirst—weig,h them.
Sample 1 will weigh 43 grains PI 2 If 43 „ 33 3 ft 43 „ 2) 4 If 42 „ 5 If 37 „ Samples 6, 7, 8 37 „ " The cotton having increased in weight from 75 to 50 per cent., according to the quantity of water added.
" We now proceed to test the solubility of these twelve samples of gun-cotton in ether, S. G. •750, and also to ascertain the various pro perties of the film produced when the solution is poured upon a glass plate. Observe that ether, at -750, contains a proportion of alcohol and water ; the S. G. of absolute ether, being only -720.
" Weigh two grains of each sample of gun-cotton, and test their respective solubility in half an ounce of ether.
Samples 1, 2, and 3, will be found to be insoluble. Sample 4 looks more gelatinous, and seems incline,d to dissolve. Sample 5 dissolves completely on shaking the bottle. Samples 6, 7, 8, 9, 10, are soluble ; 11 partly so ; 12 not at all.
" Now compare the different samples of cotton. The first three or four are long and fibrous, the next three or four are somewhat shorter, the last three or four become very short, and break up into little short shreds, many of which are lost in the washing.