SCIENTIFIC SUMMARY. 
213 
crystal corresponds to a definite unit. Dr. Beaumetz has already employed 
this preparation with success in yarious cases, especially in locomotor ataxy. 
A new Medical Magneto-electric Machine^ which we have much pleasure 
i in recommending to the notice of our medical readers, has been constructed 
I by Mr. John Browning, philosophical in- 
i strum ent maker, Minories, E.C. The 
i objection to the use of this form of in- 
I duction coil hitherto has been the fact 
that the currents are rapidly and con- 
stantly, if we may use the expression, 
reversed. This difficulty has been over- 
come in the apparatus represented in the 
adjoining cut by the employment of an 
ingenious commutator, which, as the 
wheel revolves, transmits all the positive 
currents along one pole, and all the ne- 
gative ones along another. Thus this 
machine, while free from the smell, liability to accidents, injury from corro- 
sive acids, &c., so common in the volatile induction coil, has all the advantages 
of this instrument ; and while it forms an ornamental appendage to the con- 
sulting room, it is always ready for use by the practitioner. 
Improvements in Carbolic Acid .- — Mr. Grace Calvert, who has done so much 
to improve the carbolic acid of commerce, and to cheapen this substance by 
simplifying the processes for its preparation, made the following remarks in 
the course of a lecture delivered before the French Society for the En- 
couragement of National Industry. Having described his many efforts 
to induce the profession to employ carbolic acid, he went on to say : But 
the tarry and sulphuretted odour which it still possessed was a serious 
obstacle to its application. I soon succeeded in overcoming this difficulty, 
and towards the end of the year 1864 our firm was in a position to deliver, 
in considerable quantities, carbolic acid deprived of sulphuretted compounds, 
and therefore fit for all medicinal uses. But I am glad to say that the series 
of improvements in the manufacture of pure carbolic acid, or phenic 
alcohol, did not stop there, for towards the end of last year I discovered a 
process which now enables me to show you a product completely deprived 
of all disagreeable odour and tarry flavour, and, in fact, as pure, though 
extracted from tar, as if it had been produced artificially by the help of the 
reactions recently discovered by Mesrs. Wurtz and Kekule, phased upon the 
direct transformation of benzine into carbolic acid, or by the well-known 
changes by which it may be obtained from salicylic acid or nitro-benzoic. 
This new phenic or carbolic acid is distinguished from Laurent’s in being 
soluble in 20 parts of water, whereas the latter requires 33. It is fusible at 
41°, instead of 34°, and boils at 182°, instead of 186°, but it gives, like 
Laurent’s, the blue colour described by M. Berthelot when mixed with 
ammonia, and to the solution is added a small quantity of a hypochlorite. 
The same effect is also produced when you expose to the vapours of 
hydrochloric acid a chip of deal soaked in this pure carbolic acid. 
Respiration in Cattle. — M. Reiset’s researches on this subject are of in- 
terest, since the experiments were conducted on a large scale, his receivers, 
