382 THE POPULAR SCIENCE MONTHLY. 



the latter, and froni it obtain the iodide by the action of potas- 

 sium hydrate or caustic potash. 



Iodine, as a commercial body, has been subject to great fluctu- 

 ations 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 Algce are not fibrous in their structure ; nor is it sur- 

 prising to find sea-weed quite extensively used as a fuel among a 

 tenantry so poverty-stricken, and in a country so bare of combus- 

 tibles. 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. 



BIRDS WITH TEETH. 



By OTTO MEYER, Ph. D. 



THE 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 per- 

 fection, 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 



