Table 1. Chemical analysis of ammonium pentaborate tetrahydrate, NH₄B₅O₈·4H₂O.

Gram molecular weight = 272.150 g

	Percentage
	PCBCa	Theoretical	This work
(NH4)2O	9.52	9.57	9.43
B2O3	63.84	63.96	63.59
H2O	…………	26.47
Cl	0.000017
SO3	.00006
Fe	.00005
Heavy metals as Pb	.00015
As2O3      Less than..	.00002
P2O5       do	.00005
Mn          do	.00001
$\begin{array}{l}{\text{SiO}}_2\\ {\text{Al}}_2{\mathrm{O}}_3\\ \text{CaO}\\ \text{MgO}\\ {\text{Na}}_2\mathrm{O}\end{array}\}--------------\{\text{Less than sensitivity of Pacific Coast Borax Co}.,\text{methods}.$
(NH4)2O:B2O3 Ratio	1:5.01	1:5	1:5.07

^aPacific Coast Borax Company.