to the dark 
( 452 ) 
somewhat smaller, and thus give rise 
chromospheric lines. 
In explaining further particulars regarding the appearance of 
chromospheric lines one will have to reckon with the fact, that the 
refracting power of the solar atmosphere is not symmetrical on both 
sides of an absorption line (cf. fig. 8, plate I, Proc. Roy. Acad. 
XII, p. 283), but on an average greater vtfith R-light than with 
V-light. That asymmetry is in general greater with weak lines than 
with stronger ones, and must increase when we pass from the red end 
of the spectrum to the violet end, if the presumption proves correct, 
that the refracting power R 0 A 0 of the solar atmosphere for waves 
not belonging to a region of the spectrum where anomalous disper¬ 
sion prevails, gradually increases from the red to the violet. 
ChemiBtry. — “On derivatives of piperazine” By Prof. Franchimont 
and Dr. E. Kramer. 
In October 1908 Dr. W. A. van Dorp Jr. made known the results 
on piperazine derivatives. Among other things he 
of his research 
had found that by the action of two mols. of formaldehyde and 
two mols. of hydrogen cyanide on piperazine, piperazino N(di) 
acetonitrile was obtained. From this nitrile, which in aqueous 
solutions gives no compounds with acids, he prepared the corre¬ 
sponding amide piperazino N(di) acetamide, which did combine with 
acids such as hydrogen chloride (2 mols.), and piperazino N(di) 
acetic add, which also yielded compounds with acids. He did not 
succeed in preparing esters of this acid owing to the insolubility of 
the hydrochloride compound of the acid in alcohol. 
We have now succeeded in obtaining the esters of this acid by 
starting from the compound of the acid with sulphuric acid; this 
compound contains one mol. of sulphuric acid and two mols. of 
water to each mol. of piperazino N(di) acetic acid. It was heated 
with an excess of sulphuric acid and alcohol ami thus yielded the 
sulphuric acid compound of the ester, which is crystalline and 
soluble in water; on treatment with bases, or carbonates under a 
layer of ether or benzene, the sulphuric acid is abstracted. The 
methyl ester of piperazino N(di) acetic acid then consists of a colour¬ 
less, crystallised substance m.p. 63°, soluble in water, also in ether 
and benzene. The ethyl ester m.p. 47°.5, is also crystalline and 
readily soluble in water, alcohol, ether, and ligroin and very 
readily so in benzene and chloroform. Being tertiary amines, both 
