Page:Popular Science Monthly Volume 36.djvu/396

382 the latter, and from it obtain the iodide by the action of potassium hydrate or caustic potash.

Iodine, as a commercial body, has been subject to great fluctuations in price. It has ranged from a minimum of $1.50 to a maximum of $9.50 per pound, and is at present quoted at the fairly constant figure of $4 per pound.

This harvest of sea-weed, whose transformation into iodine has been briefly traced, has been to a certain extent the subject of other industrial applications. In Ireland and the Channel Islands the weeds are used directly as a fertilizer. Its advantages in this line are chiefly felt in the Irish potato crop, where the potash of the sea-weed supplies a most important ingredient of that staple tuber. The presence, also, of small proportions of the earthy phosphates increases its value for fertilizing purposes. Attempts have been made to utilize these weeds in the manufacture of paper and textile goods, but with little or no success, owing to the fact that the true Algæ are not fibrous in their structure; nor is it surprising to find sea-weed quite extensively used as a fuel among a tenantry so poverty-stricken, and in a country so bare of combustibles. But the chief value of the sea-weed harvest remains in the monopoly of iodine which its tissues possess.

Despite its many wasteful drawbacks, the kelp industry shows the respectable annual yield of six million dollars, much of which finds its way into the pockets of a very destitute tenantry. In those districts where the winter supply is carefully gathered and burned, the production of kelp has had very beneficial effects by employing and remunerating the most indigent classes at a time when they would otherwise be totally unproductive.



HE birds of our present world, however different they may be from each other in size, shape, color, etc., are remarkably uniform in their anatomical construction. Adapted to a life in the air, they all possess bones which are more or less pneumatic that is, contain air-cavities, to lessen the weight of the skeleton. Altogether the reduction of weight has been brought down to perfection, and a flying bird carries very little, if any, unnecessary substance. Locomotion in the air requires, further, a vigorous action of the wings, and such a motion could hardly be executed in presence of a loose and shaky body. But the skeleton of the body of a bird is not loose; on the contrary, it is very solid. The vertebrae of the backbone are grown together and form a firm 