SCIE.NTIFIC SUMMARY. 
307 
furnish the student with a connected outline of the leading facts of che- 
mistry in their relations to each other. It will he essentially descriptive in 
its character, and aim at calling to mind, in as few words as possible, the 
ascertained origins, properties, and metamorphoses of chemical substances. 
It will include a systematic account of the monad, diad, and triad non- 
metallic elements, and their principal combination with each other; of 
silicon and carbon with its series of methylic, formic, and cyanic compounds ; 
and of the various metals, arranged, as far as practicable, in natural groups, 
with their respective series of halides, oxides, and oxisalts, &c. 
The Constitution of the Coal-tar Gases is the title of a paper some time 
since read before the Vienna Academy by Herr Tulsowshi. His observations 
tend to prove that the entire series of these basic substances, with their nu- 
merous derivatives, take their origin most probably from one and the same 
carbide of hydrogen, the as yet hypothetical combination triphenylene. 
Citric and Isocitric Acid. — Herr Rochleder of Prague publishes the follow- 
ing abstract of a recent inquiry on these acids: — A solution of citric acid, 
whose permanence is insured by the addition of dilute sulphuric acid, when 
placed in contact with sodium amalgam, gives rise to an acid of the same 
composition as citric acid — isocitric acid — which may be obtained pure by 
simply decanting. From this, isocitrate of lead may be procured in the 
ordinary way, and by decomposing this by sulphuretted hydrogen the acid 
is obtained perfectly pure. It soon solidifies to a mass containing long and 
delicate crystals. The isocitrates are very little known ; when submitted 
to dry distillation, they hardly give any product but citraconic acid. 
The New Laboratory at Leipsic, which has been completed, is said to be 
the largest and most commodious one in all Germany. 
A Phosphorus Holder. — A suggestion has been made by Mr. E. Kernan, 
in a letter to the Chejnical News, June Ilth, which, we doubt not, may be 
found useful by lecturers and others engaged in demonstration: — A few 
inches of lead tube, 5-in. bore, is contracted to an open cone, at one end. As 
much phosphorus as one may choose is put into the cone of the tube ; the 
phosphorus is made to project slightly from the cone ; the upper part of the 
tube is filled with water, and corked. Thus is had a phosphorous ‘‘ crayon ” 
perfectly safe in the hand for luminous writings, &c. To put in the phos- 
phorus, as much as may be required is melted in a conical glass, or test-tube, 
the cone of which is larger than that of the lead tube. This is put standing 
in the melted phosphorus, which fills the cone and tube to its own outside 
level. When cold, there is a nice projecting crayon, from the form of the 
glass. Any phosphorus outside the lead tube may be melted oft’. To renew 
the writing point, a test-tube,, conical below, is fitted to the cone of the 
lead ; the whole held in warm water for a minute, as much phosphorus 
flows out as forms a new point. 
Pressure and Chemical Action. — The Engineer states that M. Castletel 
continues his researches on these points. In one of his experiments sulphuric 
acid remained for twelve days in contact with an excess of zinc in a revolv- 
ing tube hermetically closed, without becoming saturated, and sodium 
amalgam remained pasty in water in the same circumstances. 
The Colouring Products of Garance. — According to Herr Rochleder, the 
root of garance, treated with the dilute mineral acid, supplies, besides 
