MEANS FOR PREVENTING THE BUMPING OF BOILING LIQUIDS. 151 
experiments which have hitherto been reported, have been made upon rabbits 
or frogs, and only two or three on the human subject. When a small quan¬ 
tity of aqueous solution of chloral was administered by subcutaneous injec¬ 
tion to a rabbit, the animal was thrown into a tranquil sleep of some hours’ 
duration. We understand that the results of numerous experiments on the 
human subject are about to be communicated by Dr. Liebreich to the me¬ 
dical public.* 
ON SOME MEANS FOR PREVENTING THE BUMPING OF BOILING 
LIQUIDS. 
BY HUGO MULLER, F.R.S. 
The annoyance which arises from the bumping of certain liquids when submitted to 
distillation or boiling has often attracted the attention of chemists, and various means 
have been proposed for its prevention. 
The value of pieces of platinum, charcoal, burnt clay, and other porous bodies for this 
purpose is well known, and, under certain circumstances, they are efficient enough ; yet 
there occur very frequently cases in the laboratory when these means are unavailable. 
About two years ago Pietro Pellogio (Fresenius, Zeitschr., vi. Jahrg.) proposed a very 
simple contrivance, which was stated to act very satisfactorily indeed. It consisted of a 
moderately wide glass tube, passing through the cork of the tubula of the retort, and 
nearly reaching the bottom of it, the upper end being bent at right angles and drawn’ 
out into a capillary tube. 
Having occasion to try the efficiency of this arrangement, I came to the conclusion 
that it was quite ineffective, and shortly after, G. Hager (Pharmac. Centralhalle, Bd. 9) 
confirmed the negative results I obtained. 
Quite recently E. Winkelhofer (Ber. d. Chem. Gesellsch. Berlin, p. 194, 1869) pro¬ 
posed for the same purpose the application of an electric current, which, through the in¬ 
cipient decomposition of the liquid and consequent evolution of gas, causes the ebulli¬ 
tion to become quite regular and steady. Dufour, for another, with another object in 
view, had made use of the same means. 
The application of the electric current unfortunately presupposes that the liquid 
to be distilled is a sufficiently good conductor of electricity ; and, if this is not the 
case, necessitates the introduction of such substances as shall cause the liquid to be¬ 
come a conductor. This circumstance, therefore, limits very considerably the use of 
this otherwise efficient arrangement, and it is on this account that I venture to bring 
under notice some other means which I have tested in a variety of cases, and which in¬ 
variably proved satisfactory. 
In cases where the introduction of any foreign matter into the liquid about to be dis¬ 
tilled is undesirable, I introduce through the cork in the tubula of the retort a glass 
tube, which is drawn out to a long capillary tube and pressed tightly to the bottom of 
the retort. The upper end of the glass tube is connected, by means of an india-rubber 
tube, with a generator of carbonic acid, or hydrogen, or a gas-holder containing air, 
and whilst the distillation is going on, one of these gases is passed in a slow but con¬ 
tinuous current through the liquid. Under these conditions, all bumping is avoided, 
and the distillation proceeds with the utmost facility. 
For ordinary purposes, however, I have found it still more convenient to introduce 
into the liquid about to be distilled a small fragment of sodium amalgam or, in cases 
where the liquid is acid, a small piece of sodium-tin. Methylic alcohol is well known 
to be one of the most difficult liquids to distil, yet, on the introduction of a minute piece 
of sodium amalgam or sodium-tin, it can be distilled without the slightest inconvenience. 
I found on one occasion that more than 400 grammes of methylic alcohol distilled over 
with perfect steadiness, and without exhausting the activity of a fragment of sodium- 
tin, weighing not more than 0060 gramme. 
It is, perhaps, hardly necessary to mention that the action of sodium amalgam and 
sodium-tin is due to a minute but continuous disengagement of hydrogen taking place 
during the process of distillation.— Chemical News. 
* Since the foregoing was written we have received a pamphlet of sixty pages, by Dr. 
Liebreich, entitled Das Chloralhydrat, ein neues Hypnoticum und Anastlieticum und dessen 
Anwendung in der Medicin, of which we hope to give a brief notice in our next Number. 
