666 



SCIENCE 



[N. S. Vol. XXVII. Nc 695 



United States upland varieties, because a few 

 of our upland cottons have the red spots at 

 the base of the petals. The argument is far 

 from conclusive, for red spots occur in many 

 widely different types, and are probably an 

 ancestral character of the genus. 



The seeds of this wild Jamaica cotton show 

 a very interesting diversity. In addition to 

 the lint a majority of them have a dense 

 adherent covering of brown fuzz, but on some 

 the fuzz has a dull greenish tinge, while in 

 still a third group most of the surface is 

 smooth and naked, the hairy covering being 

 limited to a tuft of brown fuzz at the base 

 of the seed, and a tuft of lint at the apex. 

 The presence of all three conditions in the 

 same lot of seeds of this primitive wild type 

 of cotton may help us to believe that similar 

 diversities inside our upland varieties do not, 

 of necessity, prove hybridization, but may 

 represent a normal range of ancestral di- 

 versity in this group of plants. 



The usual correlation of greater length and 

 smaller quantity of lint on smooth seeds also 

 holds good. The lint from the smooth seeds 

 averages 31.3 millimeters, that of the fuzzy 

 seeds 30 millimeters. The lint represents 

 16.03 per cent, of the total weight of the 

 smooth seeds, and 18.27 per cent, of the fuzzy 

 seeds. The smooth seeds weigh, without the 

 lint, at the rate of 4.23 grams per hundred, 

 the fuzzy at the rate of 4.97 grams. If the 

 fuzz were removed and weighed with the lint, 

 the proportion of fiber to seed would appear 

 still higher with the fuzzy seeds. The slight 

 increase of length of fiber on smooth seeds is 

 accompanied by a disproportionate reduction 

 of the quantity of fiber. O. F. Cook 



THE CORROSION OP IRON 



To THE Editor op Science: In a recent 

 publication under date of May 10, 1907,' 

 entitled " The Corrosion of Iron," the writer 

 discusses the possibility of using certain in- 

 hibitors in the priming coats of paints and 

 other protective coverings. The suggestion 

 was publicly made that slightly soluble chro- 



" Bulletin No. 30, Office of Public Koads, U. S. 

 Department of Agriculture. 



mates should be theoretically the best pro- 

 tectives to apply to iron and steel surfaces. 

 Numeroiis chrome pigments have been tested 

 by the writer in reference to their inhibition 

 value, the work having been done in large 

 part previous to the publication of the bul- 

 letin above cited. Owing to included impuri- 

 ties, many of the commercial chrome pigments 

 have been found to stimulate rather than 

 inhibit corrosion, and the use of these for such 

 purposes should be carefully guarded against. 

 It has been found, however, that zinc ehromate 

 and a pigment made by precipitating barium 

 and calcium chromates in molecular propor- 

 tions give excellent results in the absence of 

 impurities, such as sulphates, chlorides, etc. 

 Prussian blue has also proved itself among the 

 best of the rust inhibitors, so that excellent 

 formulse can be devised for good greens, using 

 the above pigments with small amounts of 

 pure calcic carbonate, and magnesium sili- 

 cates, etc. Certain of the basic orange chro- 

 mates also give good results. 



It has been reported that patents have re- 

 cently been applied for on a combination of 

 zinc ehromate with linseed oil as an inhibitive 

 coating for iron and steel. The details of 

 the claims can not yet be known, but in view 

 of the general publication of the writer's re- 

 sults, it does not seem that the grant of such 

 a patent would be justified. It is the policy 

 of this department to give out the informa- 

 tion it obtains for the free use of every one 

 in the country, and particularly to safeguard 

 the interests of the farmers. It would be a 

 misfortune, in case these inhibitive formulse 

 prove themselves of high protective value, that 

 their general use should be tied up by indi- 

 vidual patent claims. 



Allerton S. Cushman 

 Office of Public Roads, 



U. S. Depaetment of Agkicultuke 



THE discovery OF THE SATELLITES OF MARS 



To THE Editor op Science: In its issue of 

 November 26, 1907, the Boston Evening 

 Transcript published an article on the late 

 Professor Asaph Hall, U. S. Navy, by John 

 Eitchie. This paper contained the following 



