August 25, 1911] 



SCIENCE 



253 



We found that all these difficulties can be 

 avoided by the simple expedient of inverting the 

 cylinder and drawing a sample from the bottom 

 of the liquid. That this method gives a fair 

 sample "we have proved by drawing a sample in 

 this manner and comparing the result obtained 

 from this sample with that obtained by taking 

 samples at regular intervals during the escape of 

 a whole cylinder of the gas, plotting the results 

 obtained from these samples on rectangular dia- 

 gram paper and calculating percentages from the 

 areas so obtained. 



Oxygen was determined by absorption with 

 pyrogallate, nitrous oxide by explosion with hy- 

 drogen, and nitrogen by difference. No impurity 

 other than oxygen and nitrogen was detected in 

 the cylinders examined except in one specimen 

 which contained a small amount of carbon dioxide. 



The variation in composition in the gas as 

 drawn from the cylinder must be of significance 

 in the administration of the gas, and the method 

 of getting a fair sample should be applicable to 

 other liquefied gases such as carbon dioxide and 

 ammonia. 



A Differential Test for Chloride and Dioxide Sub- 

 stitutes: Chas. p. Pox, Akron, Ohio. 

 The reclaimed rubber trade recognizes two 

 grades or varieties of "so-called" substitutes. 

 These substitutes have their origin in certain very 

 soft rubbers which have been firmed or hardened 

 by action of chemicals. They are known as 

 ' ' chloride " or " dioxide ' ' substitutes. Often it 

 is interesting and valuable to trace the method of 

 manufacture of these grades. The following 

 method suffices: 



Fuse in a large nickel crucible a mixture con- 

 sisting of sodium or potassium hydrate and potas- 

 sium nitrate (1 to 5). Add the rubber, in fine 

 pieces, slowly, using cover on crucible and con- 

 tinuing fusion until a white mass, on cooling, is 

 obtained. Cool; dissolve in hot water, acidify 

 with nitric acid, boil thoroughly to expel carbon 



dioxide and nitrous /acid fumes and filter. Add 

 to filtrate excess of barium nitrate; a white pre- 

 cipitate indicates sulphur. Remove the barium 

 sulphate by careful filtration and add silver ni- 

 trate; a white precipitate shows presence of chlo- 

 rine. The presence of both of these precipitates 

 indicates a chloride substitute. The presence of 

 sulphur alone gives the clue to a sulphur dioxide 

 production. 



By using one gram of the substance and 10 

 grams of the fusing mixture the test is easily car- 

 ried out with definite results. A blank test should 

 always be conducted with the reagents, especially 

 those concerned in the fusion operation. In most 

 eases the blank test will give an opalescence with 

 the silver solution. However, if the amount stated 

 has been used and chlorine be present the precipi- 

 tate will be heavy enough to remove all doubts. 



Marine Fiber: Chas. P. Fox. 



American Consul John F. Newell, at Melbourne, 

 Australia, has recently called attention to the use 

 of a seaweed fiber in the manufacture of textiles. 

 This fiber has its origin in the leaves and stems 

 of Fosidenia Australis. Large quantities of this 

 fiber are found in Spencer Gulf. According to 

 the Jewell report, extensive deposits ranging from 

 four to twelve feet in thickness are found, in 

 shallow water, mixed with clay and sand and 

 shells. The material is dredged, roughly dried on 

 the beach, and then transported to the factory, 

 where it is cleaned, sorted and baled. 



The raw material is light brown, resembling 

 unbleached flax fiber. Fiber mixed with numerous 

 pieces of flat, satin-like leaves. The separate 

 fibers vary in length from one to six inches. They 

 are firm, smooth and only of slight strength. 

 This fiber finds a use in the manufacture of cer- 

 tain classes of woolens. When mixed with wool it 

 is said to weave and dye better than cotton and 

 to be much cheaper. 



Through the kindness of Mr. Holweeay, of 

 Brown & Dureau, Melbourne, we have examined 

 samples of the crude fiber and of cloth containing 

 one third marine fiber, one third wool and one 

 third cotton. In weaving, Lincoln or Crossbred 

 wool gives better results than Merino. 



This fabric weighs 8 oz. per square yard and 

 gives a tensile, per 1 in. width, of 22 lbs. for 

 both filler and warp. 



A Method of Analysis of Lead Ores: John Wad- 

 dell. 



This paper gives details of a method of deter- 

 mining lead in ores, especially those rich in lime. 



