819 



as active constituent, tetracalcic pliosi)hate, PaOgCas.CaO, which is sol- 

 uble in magnesium citrate sohition. This tetiacalcium salt changes read- 

 ily to dicalcic phosphate, and this, witli a part of the calcium set free, 

 forms thecompound(Ca3P208)3Ca(OII)2,in which the calcium hydroxide 

 is chemically bonnd, as no lime is dissolved from it by sugar solution. 

 This last compound is soluble in citric acid, but the compound 

 (Ca3P208)3CaO, which comes from it, is nearly insoluble. This 

 (Ca3P208)3CaO is formed by heating tricalcic phosphate and lime at 

 medium heat. At the temperature at which wrought iron softens tetra- 

 calcium phosphate is always formed. If the tetra salt is heated for a 

 long time at a low temperature it breaks up into CaO and (Ca:jl'2C)8)3CaO, 

 which, as mentioned above, is insoluble in citric acid. It is suggested 

 tliat the presence of insoluble phosphates in Thomas shig in connection 

 with the soluble tetracalcium phosphate is not necessarily due to insnf- 

 licient lime or to adulteration, but may be due rather to too slow cool- 

 ing of the slag or inopportune admission of air, whereby a part of the 

 tetracalcium phosphate was changed to the insoluble (Ca;jP208)3CaO. 



A sensitive reagent for albumen in urine, E. Spiegler {Ber. d. 

 (lent, cliem. Ges., 25 {1893)^ pp. 375-378). — The author describes a new 

 reagent by which traces of albumen can be recognized so small that 

 the potassium ferrocyanide reaction either gives no indication or is 

 uncertain. The reagent consists of a solution of 8 parts of corrosive 

 sublimate, 4 parts of tartaric acid, and 20 parts of cane sugar in 200 

 parts of water. The urine to be tested is acidulated with a little con- 

 centrated acetic acid to precipitate the mucin, decompose any car- 

 bonates present, and free the phosphoric acid of the alkaline phos- 

 ^phates; filtered if necessary; and then by means of a pipette slowly 

 added to the reagent by allowing the drops to run down the side of the 

 test tube in such a manner that the two liquids are not mixed but form 

 two layers. Tlie reagent is purposely made of a high specific gravity 

 to prevent mixing. If albumen is present a distinct whitish ring is 

 formed at once where the two layers meet, which is especially sharp if 

 the tube is held before a dark background, A special advantage of 

 the reaction is that urine which has been acted upon by bacteria can be 

 tested directly without first clarifying. If albumen is present the ring 

 which is formed is easily distinguished from the cloudiness caused by 

 the bacteria. 



It is said that 1 part of albumen in 150,000 can readily be detected 

 by the reaction, and if the tube is allowed to stand quietly for about a 

 minute after adding the reagent a plainly perceptible ring appears with 

 1 part to 225,000, while the limit to the sensitiveness of the potassium 

 ferrocyanide reaction is given as 1 to 50,000. 



Fungicides and insecticides, J. H. "Ponton {Ontario Agr. College 

 Expt. Station Bui. Xo. 73. April 8, 1892, pp. a). — Formuhis for a number 

 of the more common fungicides and insecticides, with brief diiections for 

 their application. 



