20 



FARMERS' REGISTER, 



"7%e respiration of animals is another source of 

 carbonic acid. — On confining an animal in a given 

 portion of atmosplieric air, over lime-water, this 

 produclion of carbonic acid is evinced by a pre- 

 cipitation. The same effect is also produced more 

 retnarlobly in oxygen gas. The production of 

 carbonic acid by respiration may be proved also by 

 blowing the air from the lungs, with the aid oi" a 

 quill, through lime-water, which will^immediately 

 grow milky. The carbonic acid, thus added to 

 the air, unfits it for supporting lil'e, not merely by 

 diminishing the proportion of oxygen gas, but 

 apparently by exerting a positively noxious effect. 

 Hence a given quatillty of air will support an an- 

 imal much longer when the carbonic acid is re- 

 moved as fast as it is formed, than v/hen suffered 

 to remain in a state of mixture. It has been (bund 

 that an atmosphere consisting of oxygen gas and 

 carbonic acid, is fatal to anin)als, though it should 

 contain a larger proportion of oxygen than the 

 air we commonly breathe." The natural consti- 

 tution of the then atmosphere, and a climate suit- 

 ed to its nature is the best for the silk-worms, and 

 for all other animals. (See Henry's Elements of 

 Chemistry article "Carbonic Acid," and Farmers' 

 Register, vol. 6, p. 628.) 



I will close this communication by commenting 

 on the following, and perhaps some other state- 

 ments, in Dr. Perrine's letter in the last No. of the 

 Register : " But sir, for the sake of the southern 

 states themselves, I should prefer a much lower 

 valuation of the leaves ; and I hope that you 

 yourself will soon demonstate that you can make 

 $4 net profit per acre, per annum, by selling on 

 the trees their leaves at 12^ cents per 100 lbs ; i. e. 

 3,200 pounds of leaves from an acre of the poor- 

 est soils." How an acre of land planted with 

 mulberry and enclosed, and cultivated too, can 

 furnish ^4 net profit, or indeed any profit, I am 

 unable to perceive ; and all who believe that this 

 estimate comes near the truth, will of course aban- 

 don the culture of silk. I venture to assert, that 

 not one person can be found in Virginia, willing 

 to expend ^4 annually on an acre of land, for the 

 prospect of having the same amount returned by 

 a nurchase of mulberry leaves. But let us see 

 how this view of the subject looks, when contrast- 

 ed with Dr. P's. admission in a former letter, that 

 200 pounds of leaves are sufficient to produce one 

 pound of reeled silk. The product of 3,200 pounds 

 of leaves, or " one acre of the poorest soil," would 

 be 16 pounds of reeled silk. 



16 pounds of raw silk at ^5 880 00 



Deduct (or rearing worms $16, reeling 



cocoons ^16, and cultivation ^4 36 00 



Net product .S44 00 



We recently sold a small parcel of reeled silk in 

 Philadelphia (the reeling not done in the best 

 style,) at 8-5 p^^" pounci ; and that the charges al- 

 lowed for " common culture" and other labor are 

 ample, will not be questioned by persons having 

 practical knowledge of the business. The op- 

 posers of the culture of silk need take no higher 

 ground than that assumed by Dr. Perrine. De- 

 monstrate that it is true, and this " humbug " will 

 die. I believe it is usual in some parts of Virgin- 

 ia to rent land for one-third part of the gross pro- 

 duct, (the tenant performing all the labor,) and i( 

 this plan were adopted with a mulberry plantation, 

 the leaves (3,200 pounds) would commmonly (iir- 



nish the landlord 5;^ pounds of reeled silk, worth 

 (the expense of reeling being deducted,) ^21 33, 

 At that price, the leaves would not be high, 

 making Dr. P.'s admission, that 200 pounds of 

 leaves make a pound of silk, the basis of one cul- 

 tivation. The owners of nuilberry plantations 

 would of course furnish a building (or the accom- 

 modation of the worms. 



In another part of Dr. Perrine's letter, we have 

 the following language : " But take my estimate 

 of 55 pounds of reeled silk per acre, and then 

 5,000,000 pounds of reeled silk, will require bu». 

 200,000 acres of the poorest soils, (and yet the 

 poorest soils only, produce 161bs. reeled silk per 

 acre,) of the southern states, or about the half of 

 one per cent, of the superficies of V^irginia. How 

 does this agree with the assumption of Judge 

 Comstock, that 35,000,000 of moras multicaulis, 

 will not suffice to supply the little state of Connec- 

 ticut, when tested by the doctrine of G. B, Smith, 

 that for a permanent plantation to make silk, there 

 should be only 2420 trees upon an acre. But as 

 the latter signed the estimate of the convention of 

 51 pounds of reeled silk per acre, less than 25,000,- 

 000 of morus multicaulis would suffice to plant 

 100,000 acre3, requisite to produce the 5,000,000 

 pounds of raw silk." 



When 2420 trees are planted to the acre, 100,- 

 000 acres would required 242,000,000, or 200,000 

 acres, 484,000,000 ; so that Dr. P.'s calculation is 

 wrong in one view to the amount of217, 000,000 and 

 in the other, 459,000,000 ; and I hold (although 

 not a speculator,) that five times the last named 

 number of trees will be requisite to make the 

 United States a silk growing country, on an ex- 

 tensive scale. There is extensive delusion,* on 

 this subject in the United Slates, and I regret that 

 one claiming to be a friend to the culture of silk 

 should be using his influence to increase it. Why 

 should we believe that the production of silk in the 

 United States cannot go beyond 5,000,000 pounds 

 annually? 



In 1800 the United States exported 16,000,000 

 pounds of cotton to Great Britain, and to France, 

 800,000 pounds ; in 1833 the export to Great Bri- 

 tain had reached 237,000,000 pounds, and that to 

 France, 1,71.3,000; besides this, in 1833, the 

 United States exported domestic manufactories of 

 cotton, as follows : 



Valued at. 



To the East Indies - - $36,000 



" China . - - . 213,000 



<> JNlexico - - - 900,000 



" the Central Republic, Columbia, 



Brazil, Buenos Ayres and Chili 1,383,567 



$2,532,567 

 And yet, as late as 1820 it was asserted confi- 

 dently by many, that Americans could not compete 

 with foreigners in the manufacture of cotton ; that 

 cotton manufactories in the United Slates might 

 maintain a sickly existence for a few years, but 

 that they would ultimately fail, and involve their 

 projectors in pecuniary ruin. Such wilt be the 

 progress of the culture and manufacture of silk in 

 the 'United States. It will meet with opposition 

 and ridicule for several years to come, and when 



* Many are making their calculations to feed one or 

 two milliong of worms in 1840, who have not trees 

 enough to sustain more than 200,000. 



