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which takes the twist out of the fibre, does injury to the strength of the yarn. I am quite sure that in many of the processes of drawing there is a greater or less injury to the twist of the fibre. This matter we cannot demonstrate by any one specimen or two specimens; it is a question of averages. It is a question which finds its solution by counting the number of fibres which may lie in any amount of yarn, and repeating the experiments until, by taking the mean of the whole, you can ascertain whether or not an injury has been done to this fibre. That is the principal mechanical injury (and that in itself is very slight) which is done to the fibre in the process of manufacture, so far as I have examined the question.
Thirdly, there may be an injury to the fibre arising from some disturbance of the particles of cellulose of which that fibre is made up. You know that in the cotton fibre, twisted as it is, the particles must be under some condition of strain. When I take a rod of any material, and twist it, and hold it in that condition, the particles of it are in various conditions of tension, and it will require very careful analysis, measurement, and calculation to detect just where the lines of strain come, and where any injury was liable to occur. Now, the cotton fibre is in that condition, and it is quite possible, looking at it theoretically, of course, that some disturbance of the molecular arrangement of that cotton fibre may be produced, so that each fibre shall have less absolute strength, and thus the strength of the yarn, depending not upon the interlocking of the fibres taken singly, but upon their united value and power of resistance, shall be impaired.
To solve this problem, I thought to bring to bear upon the fibres the test of polarized light. This test does not so far reveal any such alteration of the arrangement of cellulose particles in the cotton hair as to materially affect the value or the strength of the cotton in the processes of spinning.
This is the ground, roughly stated, which I have tried to cover in my examinations, and which, with greater or less success, I hope to demonstrate to you now.
I found that my old friend Bicknell, who had been with me in the microscopic lecture-field a good deal, had been making some experiments for one of the cotton mills in Nashua, and with his apparatus, which is the same apparatus that I am using
generally in my microscopical lectures, had visited the mill, and, under the direction of the agent, had a number of specimens prepared, and examined them by projection upon the screen ; and it occurred to me that the best thing I could do would be to introduce that very series of experiments to-day, letting you see not only the photographs of cotton fibres, which, of course,
, are but dim presentments of the truth, but the fibres themselves in their fullest enlargement upon the screen.
I propose, therefore, to exhibit cotton fibres magnified a thousand diameters in linear direction on the screen, which will afford you an opportunity of close observation nearly as well as under the microscope.
I shall take in the first place a series of objects and photographs. Here is one which I prepared for study. It is a fragment of the husk of the cotton-seed with the hairs upon it.
. This is simply shown by an ordinary projecting lens for pictures ; and you see both the thickness and fulness of the fibres as they cling to the husk of tủe cotton-seed. If you had time to step close to the screen, you would find that there were short fibres, and fibres very evidently plain instead of twisted. This is simply to show the arrangement of fibres upon the cotton-seed.
I put in next a drawing which illustrates the shape of the cotton hair as I described it to you. On the left is a green cotton hair showing the thickuess of the walls. The other is a section of a dry cotton hair, just as you receive it in the bale. All that has taken place is simply a shrinking and compression of the fibre in the centre. You have also exhibited the two pear-shaped spaces. If any injury comes to the cotton fibre, it comes on the rounded surface. It is not sharp at the edge. If there is a great amount of twist in those fibres, you see how they can be woven together without a tangle.
[Showing another preparation.]
That is the way the cotton comes from the gin, tangled just like that. The work which the cotton-gin does is to tear off those fibres. If I had a bit of seed from which the hairs had been removed, you would see that it was covered with a kind of stubble where the hairs were broken off. That same twisting and mixing up of fibres characterizes cotton in the bale, and it is the getting out of that mechanical snarling of the fibres that your carding-machines and the various kinds of machines that
you have for straightening out the fibres accomplish. They do that work.
[Exhibiting another preparation.]
That is the cotton hair and a portion of the seed. That is no photograph. It is the object itself. It is the cotton on the seed as it goes to the cotton-gin. It is torn off; and if a quantity of cotton can be taken from the bale and put under the microscope, it is found to be still twisted in that way. That is the ripe cotton,
I will take, now, a series of negatives. As I first showed the fibre, I don't think it best to take different pictures of that. Here are photographs of Egyptian cotton.
That which you see now illustrated upon the screen is just as the cotton lies together as it is taken from the bale. You can see that the fibres are tangled up. They lie crosswise in all kinds of positions; and yet each fibre bas its particular twist.
Here is another exhibit of Egyptian cotton. Here again the cotton lies massed together.
Here, on this other side, is a preparation of Porto Rico cotton. If you
will notice the fibre that comes in where I now indicate with the pointer, along in the centre between two others, you will see an illustration of what I mean by the twist of the cotton fibre itself while it is dry. If you will notice any one of these fibres, you will perceive that the appearance on the edge is different from that on the centre. That is due to the fibre being hollow and thicker at the edge than at the centre.
Here, on this other side, is an exhibit of some West India cotton of the Sea Island variety. The general appearance of these cottons is very much alike. The only difference will be in the more or less tangled condition of the fibre and in the size of the fibre itself.
Here, on another slide, which I now place in the instrument, we have some Venezuela cotton.
As an illustration of the resisting power of cellulose, or rather of the way in which it retains its mechanical arrangement after undergoing peculiar chemical changes, I will show you a bit of gun-cotton. This substance is made, you will recollect, by the replacing of three atoms of water with three atoms of nitric acid. The process of manufacture is by plunging the cotton in the acid and then washing and drying it. You would think that such a
profound chemical change as that would make great changes in the microscopic appearance of the article as well. But you will see that, optically, its arrangement of fibres is substantially the same in the one whose image is now thrown upon the screen as in the one heretofore exhibited. There is no optical distinction between the two.
Here follow a series of three cottons. You have in the image pow thrown upon the screen, & specimen of what you call middling peeler" cotton, as it comes from the bale.
Mr. PALFREY. I should like to ask how many of those strands now shown on the screen would be found in a single fibre.
Dr. BOLLES. You can just see one of those with the naked eye. When you separate cotton, and pull it out, each one of those is a thousandth of an inch in diameter.
Now, I will show you cotton after it has passed through what you call the railway head. This is not so good a photograph as some of the others; but, so far as this one specimen is concerned, you will perceive that the cotton does not present, as now projected on the screen, any appearance greatly different from that of cotton which had not been subjected to the action of the railway head.
Mr. CUMNOCK. Are those fibres put through a single or a double carding?
Dr. BOLLES. In this list of cottons, I have not the carding given as I had in some preparations which Mr. Bates gave me, and which in their examination would supply all the differences which practical gentlemen would like to know about.
We will now change our apparatus so that we can put on a high power of the microscope. In the first instance, I have a series of preparations mounted dry, which, by the kindness of Mr. Amory, I am permitted to use from the Nashua experiments; and there you will be enabled to judge yourselves as to the changes which have been operative in the cotton. I will give you the marks as the manufacturer himself gave them in the series. With this half-inch lens, you will see everything magnified eight hundred diameters, and with the other, magnified one thousand diameters. The circle which you now see on the screen is at the lantern one-tenth of an inch in diameter.
The first specimen is marked "Charleston cotton, just as it
, comes from the bale."
Those fibres are larger than you think, and they will bear close examination. I should like to have any gentleman who wishes to see just the structure of the cotton fibre, come close up to the screen and inspect it. With a lens that gives a full, field you cannot focus everything in the field at once. Now, you
have the twist and the whole structure of each fibre. There has been no manipulation of the specimen. What you see is simply the image of the dry fibre projected upon the screen. now exhibit it with a lens of higher power, magnifying one thousand diameters.
I will now replace that specimen with one marked " Mobile cotton, just as it comes from the bale.” My object in introducing these microscopical exhibitions of cotton fibres was to suggest the way in which you can study the question for yourselves. Of course it is a very delicate thing to exhibit these projections in a large room like this, and with such arrangements as I have been able to make here. But at your mills you can take preparations for the microscope of drawn yarn, or anything you please, and project the images and study them at your leisure on a large scale, and enjoy an admirable opportunity of comparison. There is still another method of illumination, which we will come to by and by.
I will take now a specimen which is marked "Charleston cotton.” There is no resource of optical science yet known that with these high powers, in projection, will give you a perfectly flat and perfectly distinct field. You have to take parts of it, and individual fibres. Perhaps Mr. Bicknell will try to find some of the ends of the fibres in the image now projected. One-tenth of an inch is the entire diameter of the circle on this slide. That would give for the image eight feet for the onetenth of an inch. What upon the slide would be one inch long, would give an image eighty feet in length. A fibre one inch long is magnified to a length of eighty feet.
Now, I wish to show you a series of these cottons as they were prepared, and I will give you the labels as they are on the slides. If the gentleman from Nashua is present, he would be the one to answer any question regarding the adjustment of the machinery through which the specimens had been passed. We