26 



And again— " Sweet Cassava has a non-poisonous jiUce. has tough 

 '' portions in the centre, hut becomes quite soft hij boiling, and is eaten 

 " like potatoes." " Cassava meal is prepared from both kinds. 

 " Tapioca is prepared by heating the moistened starch of either kind 

 " on hot plates." 



Cassareep is the juice of Bitter Cassava roots concentrated by 

 heat, Avhich dissipates the poisonous principle, and this product forms 

 the basis of the well known West Indian " Pepper-pot," as well as of 

 many celebrated sauces and relishes. In Trinidad the subject of 

 poisonous and non-poisonous properties of " Cassava" was taken up by 

 the late Ernest Francis, Esq., Island Chemist, Avho published the results 

 of his work in the proceedings of the Scientific Association of Tri- 

 nidad. Mr. Francis records that, a paper was published by him in the 

 London Analyst for April, 1877, showed the amount of prussic 

 acid yielded by a number of different samples of Bitter and Sweet 

 Cassava. This table gave the mean, highest and lowest percentages of 

 fifteen (15) samples bitter, and ten samples Sweet Cassava as follows : — 



Amount of Prussic Acid yielded by Cassava roots. 



Sweet. 



Mean ... 



Highest 



Lowest 



•0168 

 •0238 

 •0113 



Mean ... 



Highest 



Lowest 



Bitter, 



•0275 

 •0442 

 •0132 



Mr. Francis remarks that the samples indicated in the Table were 

 obtained from as many soui-ces as possible and care was taken to avoid 

 substitution of one kind for another, and calls attention to the dis- 

 covery that the so-called sweet or harmless Cassava not only yielded 

 Prussic Acid but the quantity obtained from it so nearly equalled that 

 from the bitter that no line of distinction could be dratvn between them. 



Many and grave are the doubts to which a record of this kind 

 gives rise, and when we find it stated that, there is also one ivith a 

 non-poisonous juice, the subject becomes one of further difficulty. 



1st. It becomes fairly clear that, either we have not the true non- 

 poisonous variet}^ in Trinidad, or that Francis did not find it, or 

 2ndly. That there is over confidence in attributing non-poisonous 

 properties to the Sweet Cassava. 



To carry the investigation further I have written to Jamaica to 

 try and obtain roots of the said "non-poisonous^^ kinds which will be 

 grown side by side with those which are taken for Sweet Cassava here, 

 from which experiment it is hoped a further light may be shed upon 

 this most difficult question. It may be mentioned that the writer and 

 his family suffered poisonous effects from eating what in Jamaica is 



