The natural form of UN 2716 1,4-Butynediol PG III is a solid organic compound. Therefore DGD Section 4.2 Blue Page describes this substance by using the unit of kilogram. When shipping this substance in a liquid state dissolved in water, as stated in the 3rd bullet point under Exception of DGR 126.96.36.199, when the physical state has changed (solid, liquid and gas), unless the Blue Pages do not carry this substance in liquid form, a new UN number and a new PSN must be selected by using the generic or n.o.s. Table 4.1.A. Since there are no appropriate name in the Specific entries for Div. 6.1, you move over to the General entries where you find UN 2810 Toxic liquid, organic, n.o.s. (1,4-Butynediol mixture). This is the correct UN number and PSN of this liquid substance. PG III and PI 655 Max 60L. Since it is a liquid, two Orientation labels are needed on opposite sides. If the packages are concealed in an Overpack, the Arrow Sign must also appear on two opposite sides of the overpack.