On the Efficacy of Paragreles. 37 



during the winter, and to give two or three ploughings in the. 

 summer. The former possesses a color more fixed, a stronger 

 odour, and a taste quite aromatic, and slightly bitter. The 

 latter a taste more mucilaginous and herbaceous, and evi- 

 dently a less degree of strength. From chemical analysis, first 

 by M. Henry, and afterwards by the celebrated M. Caven- 

 ton:* we find that one hundred parts of China rhubarb, contain 

 seventy four parts soluble in alcohol and water ; a like quan- 

 tity of the cultivated Rheum Palmatum, furnished but sixty 

 four, the Rheum Compactum but fifty, the Rheum Undula- 

 tum but thirty two, and the Rhaponticum but thirty. Thus 

 the Rheum Palmatum is proved to be the most active of the 

 indigenous rhubarbs,but is inferior to that of China. It will be 

 well to observe here, that the root of English and French 

 rhubarb was of three years growth, while the exotic, furnish- 

 ed by commerce, was at least seven or eight years of age. 

 It has been proved by observation, that the strength of the 

 indigenous rhubarb increases with its age, but as it cannot, 

 from circumstances already quoted, attain the age of the ex- 

 otic, it never can equal it in strength. Numerous experi- 

 ments, made by Dr. Geoffrey, M. Itard, and M.Ribes, in sev- 

 eral public institutions of France, prove, that the indigen- 

 ous rhubarb is purgative, and may be substituted for the ex- 

 otic, in pharmaceutical preparations, by employing one fourth 

 more than the latter. 



Art. VIII. — On the Efficacy of Paragreles. 



The efficacy of Paragreles, in affording protection against 

 the ravages of hail, appears to be too well ascertained to ad- 

 mit of doubt ;t and we are not certain that the fact is "in 

 opposition to the theories of the learned." There is an ex- 

 planation, in consistency with these theories, which seems to 

 be so simple and obvious, that we shall deem it strange, if it 

 has not occurred to those who have applied their minds to 

 the investigation of the subject. Not having access to ex- 

 tensive sources of information, we are unable to say whether 

 this is the case or not. 



It is a defect in the common theory of the foimation of 

 hail, — that it does not embrace all the observed facts. From 



* Bulletin des Sciences Medicales, Avril, 1826. 



t See Vol. 10, p. 196. Vol. 12, p. 398 of this Journal. 



