Natural Science News. 



VOL. II. No. 7. ALBION, N. Y., MARCH 14, 1896. Weekly, $1.00 a Year 



Natural Science News. 



A Weekly Journal Devoted to 

 Natural History. 



FRANK H. LATTIN, Editor and Publisher, 

 ALBION, N. Y. 



Correspondence and items of interest to the 

 student of any of the various branches of the 

 Natural Sciences solicited from all. 



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 Spiders' Silk. 



If you can picture to yourself a 

 mass of pure and yellow gold, 

 which not only reflects the light as 

 from a smooth and polished sur- 

 face, but which has all the depth 

 and softness of liquid amber, you 

 may realize in some degree the 

 wonderful appearance of a sheet of 

 spiders' silk as seen in the sun- 

 shine; and even in the shade its 

 luster is greater than that of gold. 

 But to compare the silk with gold 

 is to tell only one half of the story; 

 for the same spider yields silver as 

 well, so that you may draw from 

 its body a thread of gold or a 

 thread of silver, or both threads 

 together; their union giving silk of 

 a light yellow color. 



These two differently-colored 

 silks are drawn from two different 

 parts of the spinning organ, which 

 will be described hereafter; and 

 not only are their colors thus dis- 

 tinct, but also their other physical 

 properties;for the yellow is elastic, 

 and may be stretched slightly and 

 regain its former length, while the 

 white is inelastic, and at once 

 crinkles up when tension is remov- 

 ed during the process of drawing 

 it from the spider. The two kinds 

 of silk are employed also in the 

 construction of different parts of 

 the web; but that has been suffi- 

 ciently described elsewhere. 



Beauty and strength are natural 

 partners, and we do not look in 

 vain for the latter quality in spid- 

 ers' silk. It is indeed something 

 prodigious as compared with even 

 the strength of metals. A bar of 

 iron one inch in diameter will sus- 



tain a weight of twenty-eight tuns; 

 a bar of steel fifty-eight tuns, and, 

 according to computation based 

 upon the fact that a fiber only one 

 four-thousandth of an inch in di- 

 ameter will sustain fifty-four grains, 

 a bar of spiders' silk an inch in di- 

 ameter would support a weight of 

 seventy-four tuns. 



DISADVANTAGES OF SPIDERS' SILK. 



Aside from its excessive fineness, 

 the only thing to be said against 

 the silk is the small quantity which 

 a single spider will yield, as com- 

 pared with the production of a 

 silk-worm. And when it is admit- 

 ted that the latter spins a big co- 

 coon which yields upon the aver- 

 age, three hundred yards of silk, 

 weighing about three grains, while 

 the average length which can be 

 reeled from a spider at one time is 

 only one hundred and fifty yards, 

 which is so much finer as to weigh 

 but one-twentieth of a grain, our 

 quantitative comparison looks 

 rather discouraging and lessens the 

 satisfaction we had derived from 

 the previous comparison of quality 



But there are several other facts 

 to be considered which tend to 

 greatly reduce this discrepancy be- 

 tween the production of the two 

 insects; some of these relate direct- 

 ly to the one and some to the oth- 

 er. 



Let us first reduce the silk fur- 

 nished by the worm from its ap- 

 parent to its real amount. Three 

 grains represents the average gross 

 weight of silk yielded by one co- 

 coon; but the fiber is so covered 

 with gum which would materially 

 interfere with its manufacture that 

 it has to be cleansed by prolonged 

 boiling in soap and water, which 

 process costs each cocoon one 

 quarter of its weight, leaving the 

 real amount of available silk sup- 

 plied by each worm, two and a 

 quarter grains; but even this is for- 

 ty-five times the yield of a single 

 spider, and any practical inquirer 

 will not gain much comfort from 

 the comparison. Having now 

 placed the worm's production in 

 its true light, what can we say of 

 the spider to increase the state- 

 ment of its yield? So far from be- 

 ing destroyed, as :^ the worm, for 

 the sake of one cocoon, and there- 

 by being prevented from further 

 service in way of laying its eggs, 

 the spider is not at all injured by 

 the reeling process and after a day 

 or two of rest, is ready '.o yield us 



a second hundred and fifty yards, 

 more or less, and then a third and 

 a fourth, until it has been reeled 

 from say twenty times in the course 

 of a month, nor is this probably 

 the limit of their capacity, under 

 favorable conditions, but it will be 

 seen that, even granting it to be so, 

 and its season to be limited to a 

 month, the spider of a whole sea- 

 son is twenty times as valuable as 

 the spider of a single day, and the 

 total yield would be about three 

 thousand yards weighing just one 

 grain. Now, the worm yields only 

 two and a quarter times as much 

 as this, and that is the end of it. 

 Like the swan, it expends all its 

 life in a last effort; but the spider, 

 like the canary, does something 

 every day, and when no longer able 

 to produce silk, can provide for fu- 

 ture generations by laying five hun- 

 dred or more eggs. 



Admitting then that a worm 

 yields two and a quarter times as 

 much as a spider, what is the num- 

 ber of each required for a piece of 

 woven silk? A yard of cloth va- 

 ries greatly in weight, and some- 

 what too in quality, and of course 

 in cost; the quality we cannot here 

 consider, but as to weight and cost, 

 a cheap silk at two dollars and fifty 

 cents weight from one-half to three- 

 fourths of an ounce per yard. A 

 rich silk at from six to ten dollars 

 weighs two ounces or a little over. 

 And between these two, the ordi- 

 nary grades in which the majority 

 of people are interested cost from 

 three to five dollars per yard, and 

 weigh from one to one and a quart- 

 er ounces. 



An ounce is four hundred and 

 thirty-seven and a half grains 

 (avoirdupois), and as each spider 

 yields one grain, it will require, in 

 round numbers, four hundred and 

 fifty to produce a yard of silk; or 

 fifty-four hundred for an ordinary 

 dress pattern of twelve yards. The 

 number of worms required for the 

 same is to be ascertained by divid- 

 ing those figures by two and a 

 quarter, which makes, in round 

 numbers, two hundred worms for 

 a yard, and twenty-four hundred 

 for a dress. 



And now supposing ( for the sake 

 of comparison ) that each spider 

 costs as much time and trouble and 

 money as a worm, and that there- 

 fore, a fabric of spiders' silk costs 

 two and a quarter times as much 

 as one of ordinary silk, that fact 

 by no means indicates that the for- 

 mer is not worth having. 



