The book, written in 1849 (Oops, sorry it was published in 1900. Even worse!), is essentially an example of Pre-Adamite thinking, which contends that there WERE people on the planet before God created Adam and Eve, and that these individuals, Negroes, were the children of Ham and inferior to the children of Adam.
The book further purports to "explode" the theory of Evolution, using the revealed truth in the Bible, and uses that argument to maintain that human beings were created in the image of God while the Negroes were to be ruled over and dominated by the superior white race.
It is an incredibly ugly piece of "literature" which illustrates how incredibly far we have come in the last hundred plus years since its creation.
If you can stomach it the entire book can be viewed here.
However I would caution you against it until you have something besides coffee in your system. The term stomach churning barely does this vile piece of crap justice.