4 Notes: oN SCIENTIFIC RESEARCH. tite: tenis av a 
= Py the “identification and estimation of coumarin: m | artificial boqulla. ppl acin comp. 
2. OT of this Report. 
AS to ‘the identification of Hey Menss see p. 56. of this depart: we 
* 
"Concerning the smell as being used as analytical cr ee vide p. 105 of this Report. 
x 0 the estimation of menthol. Mm peluison with Te and tae comp. p. 69 of 
Bis Report. a er ee : f 
He the estimation or pulegone cae of other Ketones. in American pennyroyal ou, see 
a Ge of ae Report. Be Re eS . 
_ As to ‘some methods for Le oil of hopentine, compare p. 51 of this Report 
On the use. af Mymalsulphophtalein as indicator in _acidimetric work, vide p. ee of | 
3 this Se on ee Dag es 
a eae . cpeere ee | : Physical Notes. ee 
e. * Cbriect Ptcclion of hoop points. - nee Although. the boiling nein. of a body iS 
an important criterion, and aimoueh a vast amount of literature has accumulated as ~ 
| to how that constant has to. be taken, nevertheless the. 
“sources of errors are frequently not taken into due con- 
sideration. Theoretically it is agreed upon that reliable 
results are only obtainable when the liquid, the vapour, » 
* _and the mercury thread of the thermometer are of the Vay 
same temperature; in practice, oe blunders are com- 
“mitted in this respect. _ ; 
-” Th: Paul and K. Schantz’), for instance, demonstrate 
_ that the usual boiling-point method for the identification 
| of pure bodies (official in the Ph. Germ.) — - boiling flask 
gee in Babo’s air-bath - — is faulty to a great extent. | 
order to bring the liquid to its boiling point the air . 
2 bath must be heated comparatively high. This super-. 
| heating manifests itself principally towards’ the end of 
t e distillation, when only a little substance is in. the 
_ flask, and gives rise to an increase of the temperature 
& of both the vapour ‘and the thermometer, as was proved 
ayy a series of boiling tests with water and other liquids, 
where in lieu of a boiling point, constantly a boiling | ree 
range of a couple of deg. Cent. was observed. The 
E diagram illustrates which differences come into con- 
ape / 
100-0 
Be 
= (a) with the ordinary Hask 
~ 
bt b) with Kahlbaum S 
Still ee 
_ Borling temperature 
_ Sideration, curve (a) giving the boiling point in an meal Fl Savalas 
‘or Distillate 
ordinary flask, curve (b) with use of a still- head — ee 
~ according to Kahlbaum. 
An additional error of the Ph. G. pained is that a ae of the mercury ttireadl of 
the thermometer projects beyond the flask, which circumstance becomes noticeable 
Beccally with Bee Boece ile and which i is eliminated only with difficulty. 
i 
= 
« 
a 
Y Arch. der, Pharm. 5% (1919), 87. 
